Method for transmitting or receiving signal in wireless communication system supporting unlicensed band, and apparatus supporting same

ABSTRACT

The present invention relates to a wireless communication system and, in particular, to a method and an apparatus therefor, the method comprising: receiving first downlink control information (DCI) including downlink scheduling information and information on a HARQ-ACK feedback type; transmitting a HARQ-ACK feedback regarding a first physical downlink shared channel (PDSCH) corresponding to the downlink scheduling information, on the basis of the HARQ-ACK feedback type indicating a first type; and delaying transmission of the HARQ-ACK feedback regarding the first PDSCH or transmitting a previously-received HARQ-ACK feedback regarding a second PDSCH, on the basis of the HARQ-ACK feedback type indicating a second type.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application under 35 U.S.C. § 371of International Application No. PCT/KR2019/010180, filed on Aug. 12,2019, which claims the benefit of Korean Application Nos.10-2019-0057228, filed on May 15, 2019, and 10-2018-0094061, filed onAug. 10, 2018. The disclosures of the prior applications areincorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a method and apparatus used in awireless communication system and, more particularly, to a method oftransmitting and receiving a signal in a wireless communication systemsupporting an unlicensed band and apparatus for supporting the same.

BACKGROUND ART

The necessity for mobile broadband communication more improved than theconventional radio access technology (RAT) has increased as a number ofcommunication devices has required higher communication capacity. Inaddition, massive machine type communications (MTC) capable of providingvarious services anytime and anywhere by connecting a number of devicesor things to each other has been considered as a main issue in the nextgeneration communications. Moreover, a communication system designcapable of supporting services sensitive to reliability and latency hasbeen discussed. The introduction of next-generation RAT consideringenhanced mobile broadband communication (eMBB), massive MTC (mMTC),ultra-reliable and low-latency communication (URLLC), etc. has beendiscussed. In the present disclosure, the corresponding technology isreferred to as new radio access technology (NR), for convenience ofdescription.

DISCLOSURE Technical Problem

The object of the present disclosure is to provide a method oftransmitting and receiving a signal in a wireless communication systemsupporting an unlicensed band and apparatus for supporting the same.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

Technical Solution

The present disclosure provides a method and apparatus for transmittingand receiving signals in a wireless communication system supporting anunlicensed band.

In one aspect of the present disclosure, a communication method of anapparatus in a wireless communication system includes receiving firstdownlink control information (DCI) including downlink schedulinginformation and information about a hybrid automatic repeatrequest-acknowledgment (HARQ-ACK) feedback type, based on the HARQ-ACKfeedback type being indicated as a first type, transmitting an HARQ-ACKfeedback for a first physical downlink shared channel (PDSCH)corresponding to the downlink scheduling information, and based on theHARQ-ACK feedback type being indicated as a second type, pending thetransmission of the HARQ-ACK feedback for the first PDSCH, ortransmitting an HARQ-ACK feedback for a previously received secondPDSCH.

In another aspect of the present disclosure, an apparatus used in awireless communication system includes a memory and a processor. Theprocessor is configured to receive first DCI including downlinkscheduling information and information about an HARQ-ACK feedback type,based on the HARQ-ACK feedback type being indicated as a first type,transmit an HARQ-ACK feedback for a first PDSCH corresponding to thedownlink scheduling information, and based on the HARQ-ACK feedback typebeing indicated as a second type, pend the transmission of the HARQ-ACKfeedback for the first PDSCH, or transmit an HARQ-ACK feedback for apreviously received second PDSCH.

The downlink scheduling information may include a first field. When theHARQ-ACK feedback type is indicated as the first type, payload of theHARQ-ACK feedback for the first PDSCH may be determined based on a valueof the first field, and when the HARQ-ACK feedback type is indicated asthe second type, whether to pend the transmission of the HARQ-ACKfeedback for the first PDSCH or payload of the HARQ-ACK feedback for thesecond PDSCH may be determined based on the value of the first field.

The first field may include one of a transmission timing of the HARQ-ACKfeedback for the first PDSCH, information indicating pending of thetransmission of the HARQ-ACK feedback for the first PDSCH, and atransmission timing of the HARQ-ACK feedback for the second PDSCH.

The HARQ-ACK feedback type may be indicated by a 1-bit flag in the firstDCI. When the 1-bit flag indicates the first type, the first field mayinclude a transmission timing of the HARQ-ACK feedback for the firstPDSCH, and when the 1-bit flag indicates the second type, the firstfield may include information indicating pending of the transmission ofthe HARQ-ACK feedback for the first PDSCH, and a transmission timing ofthe HARQ-ACK feedback for the second PDSCH.

Second DCI that does not include downlink scheduling information mayfurther be received. A transmission timing of the HARQ-ACK feedback forthe first PDSCH and information indicating pending of the transmissionof the HARQ-ACK feedback for the first PDSCH may be received in thefirst DCI, and a transmission timing of the HARQ-ACK feedback for thesecond PDSCH may be received in the second DCI.

The HARQ-ACK feedbacks may be transmitted in an unlicensed band(U-band).

The first DCI and/or the second DCI may be received during adiscontinuous reception (DRX) on duration configured for the apparatus.

The apparatus applied to embodiments of the present disclosure mayinclude an autonomous driving vehicle.

The above-described aspects of the present disclosure are only some ofthe preferred embodiments of the present disclosure, and variousembodiments reflecting the technical features of the present disclosuremay be derived and understood from the following detailed description ofthe present disclosure by those skilled in the art.

Advantageous Effects

According to the embodiments of the present disclosure, a user equipment(UE) may efficiently transmit a hybrid automatic repeatrequest-acknowledgment (HARQ-ACK) feedback for downlink data.

Specifically, a base station (BS) may efficiently indicate when anHARQ-ACK feedback is to be pended and pooled.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present disclosure are not limited to whathas been particularly described hereinabove and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiments of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 illustrates physical channels and a general signal transmissionmethod using the physical channels in a 3rd generation partnershipproject (3GPP) system as an exemplary wireless communication system;

FIG. 2 illustrates an exemplary procedure for network initial access andsubsequent communication.

FIG. 3 is a diagram illustrating a DRX cycle.

FIG. 4 illustrates a radio frame structure;

FIG. 5 illustrates a resource grid during the duration of a slot;

FIG. 6 illustrates a self-contained slot structure;

FIG. 7 illustrates mapping of physical channels in a self-containedslot.

FIG. 8 illustrates an ACK/NACK transmission process.

FIG. 9 illustrates an exemplary PUSCH transmission process.

FIG. 10 illustrates exemplary multiplexing of UCI in a PUSCH.

FIG. 11 illustrates an exemplary wireless communication systemsupporting an unlicensed band applicable to the present disclosure.

FIG. 12 illustrates an exemplary method of occupying resources in anunlicensed band.

FIG. 13 is a flowchart illustrating a DL CAP for TN, signal transmissionin an unlicensed band, performed by a BS.

FIG. 14 is a flowchart illustrating UE's CAP operation for UL signaltransmission.

FIGS. 15 to 17 illustrate a signal transmission process according to thepresent disclosure.

FIG. 18 illustrates a communication system applied to the presentdisclosure.

FIG. 19 illustrates wireless devices applicable to the presentdisclosure.

FIG. 20 illustrates another example of a wireless device applied to thepresent disclosure.

FIG. 21 illustrates a vehicle or an autonomous driving vehicle appliedto the present disclosure.

BEST MODE

The following technology may be used in various wireless access systemssuch as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier frequencydivision multiple access (SC-FDMA), and so on. CDMA may be implementedas a radio technology such as universal terrestrial radio access (UTRA)or CDMA2000. TDMA may be implemented as a radio technology such asglobal system for mobile communications (GSM)/general packet radioservice (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA maybe implemented as a radio technology such as institute of electrical andelectronics engineers (IEEE) 802.11 (wireless fidelity (Wi-Fi)), IEEE802.16 (worldwide interoperability for microwave access (WiMAX)), IEEE802.20, evolved UTRA (E-UTRA), and so on. UTRA is a part of universalmobile telecommunications system (UMTS). 3rd generation partnershipproject (3GPP) long term evolution (LTE) is a part of evolved UMTS(E-UMTS) using E-UTRA, and LTE-advanced (LTE-A) is an evolution of 3GPPLTE. 3GPP new radio or new radio access technology (NR) is an evolvedversion of 3GPP LTE/LTE-A.

While the following description is given in the context of a 3GPPcommunication system (e.g., NR) for clarity, the technical spirit of thepresent disclosure is not limited to the 3GPP communication system.

In a wireless access system, a user equipment (UE) receives informationfrom a base station (BS) on DL and transmits information to the BS onUL. The information transmitted and received between the UE and the BSincludes general data and various types of control information. Thereare many physical channels according to the types/usages of informationtransmitted and received between the BS and the UE.

FIG. 1 illustrates physical channels and a general signal transmissionmethod using the physical channels in a 3GPP system.

When a UE is powered on or enters a new cell, the UE performs initialcell search (S11). The initial cell search involves acquisition ofsynchronization to a BS. For this purpose, the UE receives asynchronization signal block (SSB) from the BS. The SSB includes aprimary synchronization signal (PSS), a secondary synchronization signal(SSS), and a physical broadcast channel (PBCH). The UE synchronizes itstiming to the BS and acquires information such as a cell identifier (ID)based on the PSS/SSS. Further, the UE may acquire information broadcastin the cell by receiving the PBCH from the BS. During the initial cellsearch, the UE may also monitor a DL channel state by receiving adownlink reference signal (DL RS).

After the initial cell search, the UE may acquire more detailed systeminformation by receiving a physical downlink control channel (PDCCH) anda physical downlink shared channel (PDSCH) corresponding to the PDCCH(S12).

Subsequently, to complete connection to the BS, the UE may perform arandom access procedure with the BS (S13 to S16). Specifically, the UEmay transmit a preamble on a physical random access channel (PRACH)(S13) and may receive a PDCCH and a random access response (RAR) for thepreamble on a PDSCH corresponding to the PDCCH (S14). The UE may thentransmit a physical uplink shared channel (PUSCH) by using schedulinginformation in the RAR (S15), and perform a contention resolutionprocedure including reception of a PDCCH and a PDSCH signalcorresponding to the PDCCH (S16).

Meanwhile, in the unlicensed band of the NR system, a random accessprocess can be performed in two steps. For example, the UE transmitsmessage 1 to the BS, and receives message 2 from the BS as a response tothe message 1. The Message 1 is a combination of the preamble (S13) andPUSCH (S15) transmission, and the Message 2 is a combination of RAR(S14) and the contention resolution message (S16).

After the above procedure, the UE may receive a PDCCH and/or a PDSCHfrom the BS (S17) and transmit a physical uplink shared channel (PUSCH)and/or a physical uplink control channel (PUCCH) to the BS (S18), in ageneral UL/DL signal transmission procedure. Control information thatthe UE transmits to the BS is generically called uplink controlinformation (UCI). The UCI includes a hybrid automatic repeat andrequest acknowledgement/negative acknowledgement (HARQ-ACK/NACK), ascheduling request (SR), channel state information (CSI), and so on. TheCSI includes a channel quality indicator (CQI), a precoding matrix index(PMI), a rank indication (RI), and so on. In general, UCI is transmittedon a PUCCH. However, if control information and data should betransmitted simultaneously, the control information and the data may betransmitted on a PUSCH. In addition, the UE may transmit the UCIaperiodically on the PUSCH, upon receipt of a request/command from anetwork.

The UE may perform cell search, system information acquisition, beamalignment for initial connection, DL measurement, and so on based on anSSB. The SSB is used interchangeably with the synchronizationsignal/physical broadcast channel (SS/PBCH) block.

The SSB includes a PSS, an SSS and a PBCH. The SSB is composed of fourconsecutive OFDM symbols. Each of the PSS, the PBCH, the SSS/PBCH, andthe PBCH is transmitted on one OFDM symbol. The PSS and the SSS are eachcomposed of one OFDM symbol and 127 subcarriers, and the PBCH iscomposed of 3 OFDM symbols and 576 subcarriers. Polar coding andquadrature phase shift keying (QPSK) are applied to the PBCH. The PBCHincludes data REs and a demodulation reference signal (DMRS) REs in eachOFDM symbol. There are three DMRS REs per RB, and there are three dataREs between DMRS REs.

The cell search is a process of obtaining time/frequency synchronizationof a cell and detecting a cell ID (e.g., physical layer cell ID (PCID))of the cell by a UE. The PSS is used to detect a cell ID within a cellID group, and the SSS is used to detect the cell ID group. The PBCH maybe used in detecting an SSB (time) index and a half-frame.

The cell search process of the UE may be summarized as shown in Table 1below.

TABLE 1 Type of Signals Operations 1^(st) step PSS * SS/PBCH block (SSB)symbol timing acquisition * Cell ID detection within a cell ID group (3hypothesis) 2^(nd) Step SSS * Cell ID group detection (336 hypothesis)3^(rd) Step PBCH * SSB index and Half frame (HF) index DMRS (Slot andframe boundary detection) 4^(th) Step PBCH * Time information (80 ms,System Frame Number (SFN), SSB index, HF) * Remaining Minimum SystemInformation (RMSI) Control resource set (CORESET)/ Search spaceconfiguration 5^(th) Step PDCCH and * Cell access information PDSCH *RACH configuration

There are 336 cell ID groups, each including three cell IDs. There are1008 cell IDs in total.

The UE may perform a network access process to perform theabove-described/proposed procedures and/or methods (FIGS. 15 to 17). Forexample, the UE may receive and store system information andconfiguration information required to perform theabove-described/proposed procedures and/or methods during network access(e.g., BS access). The configuration information required for thepresent disclosure may be received by higher-layer signaling (e.g., RRCsignaling or MAC-layer signaling).

FIG. 2 illustrates an exemplary procedure for network initial access andsubsequent communication. In NR, a physical channel and an RS may betransmitted by beamforming. When beamforming-based signal transmissionis supported, a beam management process may be performed for beamalignment between a BS and a UE. Further, a signal proposed by thepresent disclosure may be transmitted/received by beamforming. Beamalignment may be performed based on an SSB in RRC IDLE mode, and basedon a CSI-RS (in DL) and an SRS (in UL) in RRC CONNECTED mode. Whenbeamforming-based signal transmission is not supported, a beam-relatedoperation may be skipped in the following description.

Referring to FIG. 2, a BS may transmit an SSB periodically (S2102). TheSSB includes a PSS/SSS/PBCH. The SSB may be transmitted by beamsweeping. The BS may then transmit remaining minimum system information(RMSI) and other system information (OSI) (S2104). The RMSI may includeinformation (e.g., PRACH configuration information) required for the UEto initially access the BS. After the SSB detection, the UE identifies abest SSB. The UE may then transmit an RACH preamble (Message 1 or Msg 1)in PRACH resources linked/corresponding to the index (i.e., beam) of thebest SSB (S2106). The beam direction of the RACH preamble is associatedwith the PRACH resources. Association between PRACH resources (and/orRACH preambles) and SSBs (SSB indexes) may be configured by systeminformation (e.g., RMSI). Subsequently, the BS may transmit a randomaccess response (RAR) (Message 2 or Msg 2) in response to the RACHpreamble in an RACH procedure (S2108). The UE may transmit Message 3(Msg 3) (e.g., RRC Connection Request) based on a UL grant included inthe RAR (S2110), and the BS may transmit a contention resolution message(Message 4 or Msg 4) (S2112). Msg 4 may include RRC Connection Setup.Msg 1 and Msg 3 may be combined and processed in one step (e.g., Msg A),and Msg 2 and Msg 4 may be combined and processed in one step (e.g., MsgB).

Once an RRC connection is established between the BS and the UE in theRACH procedure, beam alignment may be subsequently performed based on anSSB/CSI-RS (in DL) and an SRS (in UL). For example, the UE may receivethe SSB/CSI-RS (S2114). The SSB/CSI-RS may be used for the UE togenerate a beam/CSI report. The BS may request a beam/CSI report to theUE by DCI (S2116). The UE generates the beam/CSI report based on theSSB/CSI-RS and transmit the generated beam/CSI report to the BS on aPUSCH/PUCCH (S2118). The beam/CSI report may include information about apreferred beam as a result of beam measurement. The BS and the UE mayswitch beams based on the beam/CSI report (S2120 a and S2120 b).

Subsequently, the UE and the BS may perform the later-described/proposedprocedures and/or methods. For example, the UE and the BS may transmit aradio signal by processing information stored in a memory, or process areceived radio signal and store the processed radio signal in the memorybased on configuration information obtained in the network accessprocedure (e.g., the system information acquisition process, theRACH-based RRC connection process, and so on) according to a proposal ofthe present disclosure. The radio signal may include at least one of aPDCCH, a PDSCH, or an RS in DL, and at least one of a PUCCH, a PUSCH, oran SRS in UL.

A UE may perform a DRX operation in the afore-described/proposedprocedures and/or methods. A UE configured with DRX may reduce powerconsumption by receiving a DL signal discontinuously. DRX may beperformed in an RRC_IDLE state, an RRC_INACTIVE state, and anRRC_CONNECTED state. The UE performs DRX to receive a paging signaldiscontinuously in the RRC_IDLE state and the RRC_INACTIVE state. DRX inthe RRC_CONNECTED state (RRC_CONNECTED DRX) will be described below.

FIG. 3 is a diagram illustrating a DRX cycle (RRC_CONNECTED state).

Referring to FIG. 3, the DRX cycle includes On Duration and Opportunityfor DRX. The DRX cycle defines a time interval in which On Duration isperiodically repeated. On Duration is a time period during which the UEmonitors to receive a PDCCH. When DRX is configured, the UE performsPDCCH monitoring during the On Duration. When there is any successfullydetected PDCCH during the PDCCH monitoring, the UE operates aninactivity timer and is maintained in an awake state. On the other hand,when there is no successfully detected PDCCH during the PDCCHmonitoring, the UE enters a sleep state, when the On Duration ends.Therefore, if DRX is configured, PDCCH monitoring/reception may beperformed discontinuously in the time domain, when theafore-described/proposed procedures and/or methods are performed. Forexample, if DRX is configured, PDCCH reception occasions (e.g., slotshaving PDCCH search spaces) may be configured discontinuously accordingto a DRX configuration in the present disclosure. On the contrary, ifDRX is not configured, PDCCH monitoring/reception may be performedcontinuously in the time domain, when the afore-described/proposedprocedures and/or methods are performed. For example, if DRX is notconfigured, PDCCH reception occasions (e.g., slots having PDCCH searchspaces) may be configured continuously in the present disclosure. PDCCHmonitoring may be limited in a time period configured as a measurementgap, irrespective of whether DRX is configured.

Table 2 describes a UE operation related to DRX (in the RRC_CONNECTEDstate). Referring to Table 1, DRX configuration information is receivedby higher-layer (RRC) signaling, and DRX ON/OFF is controlled by a DRXcommand of the MAC layer. Once DRX is configured, the UE may performPDCCH monitoring discontinuously in performing the described/proposedprocedures and/or methods according to the present disclosure, asillustrated in FIG. 3.

TABLE 2 Type of signals UE procedure 1^(st) step RRC signalling (MAC-Receive DRX CellGroupConfig) configuration information 2^(nd) Step MACCE ((Long) DRX Receive DRX command command MAC CE) 3^(rd) Step — Monitora PDCCH during an on-duration of a DRX cycle

MAC-CellGroupConfig includes configuration information required toconfigure MAC parameters for a cell group. MAC-CellGroupConfig may alsoinclude DRX configuration information. For example, MAC-CellGroupConfigmay include the following information in defining DRX.

-   -   Value of drx-OnDurationTimer: defines the length of the starting        duration of a DRX cycle.    -   Value of drx-InactivityTimer: defines the length of a time        duration in which the UE is in the awake state after a PDCCH        occasion in which a PDCCH indicating initial UL or DL data has        been detected.    -   Value of drx-HARQ-RTT-TimerDL: defines the length of a maximum        time duration from reception of a DL initial transmission to        reception of a DL retransmission.    -   Value of drx-HARQ-RTT-TimerDL: defines the length of a maximum        time duration from reception of a grant for a DL initial        transmission to reception of a grant for a UL retransmission.    -   drx-LongCycleStartOffset: defines the time duration and starting        time of a DRX cycle.    -   drx-ShortCycle (optional): defines the time duration of a short        DRX cycle.

When at least one of drx-OnDurationTimer, drx-InactivityTimer,drx-HARQ-RTT-TimerDL, or drx-HARQ-RTT-TimerDL is running, the UEperforms PDCCH monitoring in each PDCCH occasion, while staying in theawake state.

For example, according to an embodiment of the present disclosure, whenDRX is configured for a UE of the present disclosure, the UE may receivea DL signal during On Duration.

FIG. 4 illustrates a radio frame structure.

In NR, UL and DL transmissions are configured in frames. Each radioframe has a length of 10 ms and is divided into two 5-ms half-frames.Each half-frame is divided into five 1-ms subframes. A subframe isdivided into one or more slots, and the number of slots in a subframedepends on a subcarrier spacing (SCS). Each slot includes 12 or 14OFDM(A) symbols according to a cyclic prefix (CP). When a normal CP isused, each slot includes 14 OFDM symbols. When an extended CP is used,each slot includes 12 OFDM symbols. A symbol may include an OFDM symbol(or a CP-OFDM symbol) and an SC-FDMA symbol (or a discrete Fouriertransform-spread-OFDM (DFT-s-OFDM) symbol).

In the NR system, different OFDM(A) numerologies (e.g., SCSs, CPlengths, and so on) may be configured for a plurality of cellsaggregated for one UE. Accordingly, the (absolute time) duration of atime resource (e.g., a subframe, a slot, or a transmission time interval(TTI)) (for convenience, referred to as a time unit (TU)) composed ofthe same number of symbols may be configured differently between theaggregated cells.

FIG. 5 illustrates a resource grid during the duration of one slot.

A slot includes a plurality of symbols in the time domain. For example,one slot includes 14 symbols in a normal CP case and 12 symbols in anextended CP case. A carrier includes a plurality of subcarriers in thefrequency domain. A resource block (RB) may be defined by a plurality of(e.g., 12) consecutive subcarriers in the frequency domain. A bandwidthpart (BWP) may be defined by a plurality of consecutive (physical) RBs((P)RBs) in the frequency domain and correspond to one numerology (e.g.,SCS, CP length, and so on). A carrier may include up to N (e.g., 5)BWPs. Data communication may be conducted in an active BWP, and only oneBWP may be activated for one UE. Each element in a resource grid may bereferred to as a resource element (RE), to which one complex symbol maybe mapped.

FIG. 6 illustrates a structure of a self-contained slot.

In the NR system, a frame has a self-contained structure in which a DLcontrol channel, DL or UL data, a UL control channel, and the like mayall be contained in one slot. For example, the first N symbols(hereinafter, DL control region) in the slot may be used to transmit aDL control channel, and the last M symbols (hereinafter, UL controlregion) in the slot may be used to transmit a UL control channel. N andM are integers greater than or equal to 0. A resource region(hereinafter, a data region) that is between the DL control region andthe UL control region may be used for DL data transmission or UL datatransmission. For example, the following configuration may beconsidered. Respective sections are listed in a temporal order.

1. DL only configuration

2. UL only configuration

3. Mixed UL-DL configuration

-   -   DL region+Guard period (GP)+UL control region    -   DL control region+GP+UL region    -   DL region: (i) DL data region, (ii) DL control region+DL data        region    -   UL region: (i) UL data region, (ii) UL data region+UL control        region

FIG. 7 illustrates mapping of physical channels in a self-containedslot. The PDCCH may be transmitted in the DL control region, and thePDSCH may be transmitted in the DL data region. The PUCCH may betransmitted in the UL control region, and the PUSCH may be transmittedin the UL data region. The GP provides a time gap in the process of theUE switching from the transmission mode to the reception mode or fromthe reception mode to the transmission mode. Some symbols at the time ofswitching from DL to UL within a subframe may be configured as the GP.

Now, a detailed description will be given of physical channels.

The PDCCH delivers DCI. For example, the PDCCH (i.e., DCI) may carryinformation about a transport format and resource allocation of a DLshared channel (DL-SCH), resource allocation information of an uplinkshared channel (UL-SCH), paging information on a paging channel (PCH),system information on the DL-SCH, information on resource allocation ofa higher-layer control message such as an RAR transmitted on a PDSCH, atransmit power control command, information about activation/release ofconfigured scheduling, and so on. The DCI includes a cyclic redundancycheck (CRC). The CRC is masked with various identifiers (IDs) (e.g. aradio network temporary identifier (RNTI)) according to an owner orusage of the PDCCH. For example, if the PDCCH is for a specific UE, theCRC is masked by a UE ID (e.g., cell-RNTI (C-RNTI)). If the PDCCH is fora paging message, the CRC is masked by a paging-RNTI (P-RNTI). If thePDCCH is for system information (e.g., a system information block(SIB)), the CRC is masked by a system information RNTI (SI-RNTI). Whenthe PDCCH is for an RAR, the CRC is masked by a random access-RNTI(RA-RNTI).

The PDCCH may include 1, 2, 4, 8, or 16 control channel elements (CCEs)depending on the aggregation level (AL). The CCE is a logical allocationunit for providing the PDCCH with a predetermined coding rate based onthe state of a radio channel. The PDCCH is transmitted in a controlresource set (CORESET). The CORESET is defined as a set of REGs with agiven numerology (e.g., SCS, CP length, etc.). A plurality of CORESETsfor one UE may overlap in the time/frequency domain. The CORESET may beconfigured by system information (e.g., master information block (MIB))or UE-specific higher layer signaling (e.g., radio resource control(RRC) layer signaling). Specifically, the numbers of RBs and OFDMsymbols (up to three OFDM symbols) in the CORESET may be configured byhigher layer signaling.

To receive/detect the PDCCH, the UE monitors PDCCH candidates. A PDCCHcandidate refers to CCE(s) that the UE should monitor for PDCCHdetection. Each PDCCH candidate is defined by 1, 2, 4, 8, or 16 CCEsdepending on the AL. Here, monitoring includes (blind) decoding of PDCCHcandidates. A set of PDCCH candidates monitored by the UE are defined asa PDCCH search space (SS). The SS may include a common search space(CSS) or a UE-specific search space (USS). The UE may obtain DCI bymonitoring PDCCH candidates in one or more SSs, which are configured byan MIB or higher layer signaling. Each CORESET is associated with one ormore SSs, and each SS is associated with one CORESET. The SS may bedefined based on the following parameters.

-   -   controlResourceSetId: this indicates the CORESET related to the        SS.    -   monitoringSlotPeriodicityAndOffset: this indicates a PDCCH        monitoring periodicity (on a slot basis) and a PDCCH monitoring        period offset (on a slot basis).    -   monitoringSymbolsWithinSlot: this indicates PDCCH monitoring        symbols in a slot (e.g., first symbol(s) in the CORESET).    -   nrofCandidates: this denotes the number of PDCCH candidates for        each AL={1, 2, 4, 8, 16} (one of 0, 1, 2, 3, 4, 5, 6, and 8).    -   An occasion (e.g., time/frequency resource) for monitoring PDCCH        candidates is defined as a PDCCH (monitoring) occasion. One or        more PDCCH (monitoring) occasions may be configured in a slot.

Table 3 shows the characteristics of each SS.

TABLE 3 Search Type Space RNTI Use Case Type0- Common SI-RNTI on SIBPDCCH a primary cell Decoding Type0A- Common SI-RNTI on SIB PDCCH aprimary cell Decoding Type1- Common RA-RNTI Msg2, Msg4 PDCCH or TC-RNTIdecoding in on a primary cell RACH Type2- Common P-RNTI on Paging PDCCHa primary cell Decoding Type3- Common INT-RNTI, PDCCH SFI-RNTI,TPC-PUSCH-RNTI, TPC-PUCCH-RNTI, TPC-SRS-RNTI, C-RNTI, MCS-C-RNTI, orCS-RNTI (s) UE C-RNTI, or User specific Specific MCS-C-RNTI, PDSCH orCS-RNTI (s) decoding

Table 4 shows DCI formats transmitted on the PDCCH.

TABLE 4 DCI format Usage 0_0 Scheduling of PUSCH in one cell 0_1Scheduling of PUSCH in one cell 1_0 Scheduling of PDSCH in one cell 1_1Scheduling of PDSCH in one cell 2_0 Notifying a group of UEs of the slotformat 2_1 Notifying a group of UEs of the PRB (s) and OFDM symbol (s)where UE may assume no transmission is intended for the UE 2_2Transmission of TPC commands for PUCCH and PUSCH 2_3 Transmission of agroup of TPC commands for SRS transmissions by one or more UEs

DCI format 0_0 may be used to schedule a TB-based (or TB-level) PUSCH,and DCI format 0_1 may be used to schedule a TB-based (or TB-level)PUSCH or a code block group (CBG)-based (or CBG-level) PUSCH. DCI format1_0 may be used to schedule a TB-based (or TB-level) PDSCH, and DCIformat 1_1 may be used to schedule a TB-based (or TB-level) PDSCH or aCBG-based (or CBG-level) PDSCH (DL grant DCI). DCI format 0_0/0_1 may bereferred to as UL grant DCI or UL scheduling information, and DCI format1_0/1_1 may be referred to as DL grant DCI or DL scheduling information.DCI format 2_0 is used to deliver dynamic slot format information (e.g.,a dynamic slot format indicator (SFI)) to a UE, and DCI format 2_1 isused to deliver DL pre-emption information to a UE. DCI format 2_0and/or DCI format 2_1 may be delivered to a corresponding group of UEson a group common PDCCH which is a PDCCH directed to a group of UEs.

DCI format 0_0 and DCI format 1_0 may be referred to as fallback DCIformats, whereas DCI format 0_1 and DCI format 1_1 may be referred to asnon-fallback DCI formats. In the fallback DCI formats, a DCI size/fieldconfiguration is maintained to be the same irrespective of a UEconfiguration. In contrast, the DCI size/field configuration variesdepending on a UE configuration in the non-fallback DCI formats.

The PDSCH delivers DL data (e.g., a downlink shared channel (DL-SCH)transport block (TB)) and adopts a modulation scheme such as quadraturephase shift keying (QPSK), 16-ary quadrature amplitude modulation (16QAM), 64-ary QAM (64 QAM), or 256-ary QAM (256 QAM). A TB is encoded toa codeword. The PDSCH may deliver up to two codewords. The codewords areindividually subjected to scrambling and modulation mapping, andmodulation symbols from each codeword are mapped to one or more layers.An OFDM signal is generated by mapping each layer together with a DMRSto resources, and transmitted through a corresponding antenna port.

The PUCCH delivers uplink control information (UCI). The UCI includesthe following information.

-   -   SR: information used to request UL-SCH resources.    -   HARQ-ACK: a response to a DL data packet (e.g., codeword) on the        PDSCH. An HARQ-ACK indicates whether the DL data packet has been        successfully received. In response to a single codeword, a 1-bit        of HARQ-ACK may be transmitted. In response to two codewords, a        2-bit HARQ-ACK may be transmitted. The HARQ-ACK response        includes positive ACK (simply, ACK), negative ACK (NACK),        discontinuous transmission (DTX) or NACK/DTX. The term “HARQ-ACK        is interchangeably used with HARQ ACK/NACK and ACK/NACK.    -   CSI: feedback information for a DL channel. Multiple input        multiple output (MIMO)-related feedback information includes an        RI and a PMI.

Table 5 illustrates exemplary PUCCH formats. PUCCH formats may bedivided into short PUCCHs (Formats 0 and 2) and long PUCCHs (Formats 1,3, and 4) based on PUCCH transmission durations.

TABLE 5 Length in OFDM PUCCH symbols Number format N_(symb) ^(PUCCH) ofbits Usage Etc 0 1-2 ≤2 HARQ, SR Sequence selection 1  4-14 ≤2 HARQ,[SR] Sequence modulation 2 1-2 >2 HARQ, CSI, [SR] CP-OFDM 3  4-14 >2HARQ, CSI, [SR] DFT-s-OFDM (no UE multiplexing) 4  4-14 >2 HARQ, CSI,[SR] DFT-s-OFDM (Pre DFT OCC)

PUCCH format 0 conveys UCI of up to 2 bits and is mapped in asequence-based manner, for transmission. Specifically, the UE transmitsspecific UCI to the BS by transmitting one of a plurality of sequenceson a PUCCH of PUCCH format 0. Only when the UE transmits a positive SR,the UE transmits the PUCCH of PUCCH format 0 in PUCCH resources for acorresponding SR configuration.

PUCCH format 1 conveys UCI of up to 2 bits and modulation symbols of theUCI are spread with an orthogonal cover code (OCC) (which is configureddifferently whether frequency hopping is performed) in the time domain.The DMRS is transmitted in a symbol in which a modulation symbol is nottransmitted (i.e., transmitted in time division multiplexing (TDM)).

PUCCH format 2 conveys UCI of more than 2 bits and modulation symbols ofthe DCI are transmitted in frequency division multiplexing (FDM) withthe DMRS. The DMRS is located in symbols #1, #4, #7, and #10 of a givenRB with a density of 1/3. A pseudo noise (PN) sequence is used for aDMRS sequence. For 2-symbol PUCCH format 2, frequency hopping may beactivated.

PUCCH format 3 does not support UE multiplexing in the same PRBS, andconveys UCI of more than 2 bits. In other words, PUCCH resources ofPUCCH format 3 do not include an OCC. Modulation symbols are transmittedin TDM with the DMRS.

PUCCH format 4 supports multiplexing of up to 4 UEs in the same PRBS,and conveys UCI of more than 2 bits. In other words, PUCCH resources ofPUCCH format 3 include an OCC. Modulation symbols are transmitted in TDMwith the DMRS.

The PUSCH delivers UL data (e.g., UL-shared channel transport block(UL-SCH TB)) and/or UCI based on a CP-OFDM waveform or a DFT-s-OFDMwaveform. When the PUSCH is transmitted in the DFT-s-OFDM waveform, theUE transmits the PUSCH by transform precoding. For example, whentransform precoding is impossible (e.g., disabled), the UE may transmitthe PUSCH in the CP-OFDM waveform, while when transform precoding ispossible (e.g., enabled), the UE may transmit the PUSCH in the CP-OFDMor DFT-s-OFDM waveform. A PUSCH transmission may be dynamicallyscheduled by a UL grant in DCI, or semi-statically scheduled byhigher-layer (e.g., RRC) signaling (and/or Layer 1 (L1) signaling suchas a PDCCH) (configured scheduling or configured grant). The PUSCHtransmission may be performed in a codebook-based or non-codebook-basedmanner.

FIG. 8 illustrates an ACK/NACK transmission process. Referring to FIG.8, the UE may detect a PDCCH in slot #n. The PDCCH includes DLscheduling information (e.g., DCI format 1_0 or DCI format 1_1). ThePDCCH indicates a DL assignment-to-PDSCH offset, K0 and a PDSCH-HARQ-ACKreporting offset, K1. For example, DCI format 1_0 or DCI format 1_1 mayinclude the following information.

-   -   Frequency domain resource assignment: Indicates an RB set        assigned to the PDSCH.    -   Time domain resource assignment: Indicates K0 and the starting        position (e.g. OFDM symbol index) and length (e.g. the number of        OFDM symbols) of the PDSCH in a slot.    -   PDSCH-to-HARQ_feedback timing indicator: Indicates K1.

After receiving the PDSCH in slot #(n+K0) according to the schedulinginformation of slot #n, the UE may transmit UCI on the PUCCH in slot#(n+K1). The UCI includes an HARQ-ACK response to the PDSCH. In the casewhere the PDSCH is configured to carry one TB at maximum, the HARQ-ACKresponse may be configured in one bit. In the case where the PDSCH isconfigured to carry up to two TBs, the HARQ-ACK response may beconfigured in two bits if spatial bundling is not configured and in onebit if spatial bundling is configured. When slot #(n+K1) is designatedas an HARQ-ACK transmission timing for a plurality of PDSCHs, UCItransmitted in slot #(n+K1) includes HARQ-ACK responses to the pluralityof PDSCHs.

FIG. 9 illustrates an exemplary PUSCH transmission process. Referring toFIG. 9, a UE may detect a PDCCH in slot #n. The PDCCH may include ULscheduling information (e.g., DCI format 0_0 or DCI format 0_1). DCIformat 0_0 and DCI format 0_1 may include the following information.

-   -   Frequency domain resource assignment: Indicates an RB set        allocated to a PUSCH.    -   Time domain resource assignment: Specifies a slot offset K2        indicating the starting position (e.g., symbol index) and length        (e.g., the number of OFDM symbols) of the PUSCH in a slot. The        starting symbol and length of the PUSCH may be indicated by a        start and length indicator value (SLIV), or separately.

The UE may then transmit the PUSCH in slot #(n+K2) according to thescheduling information in slot #n. The PUSCH includes a UL-SCH TB.

FIG. 10 illustrates exemplary multiplexing of UCI in a PUSCH. If aplurality of PUCCH resources overlap with a PUSCH resource in a slot anda PUCCH-PUSCH simultaneous transmission is not configured in the slot,UCI may be transmitted on a PUSCH (UCI piggyback or PUSCH piggyback), asillustrated. In the illustrated case of FIG. 8, an HARQ-ACK and CSI arecarried in a PUSCH resource.

Recently, the 3GPP standardization group has proceeded to standardize a5G wireless communication system named new RAT (NR). The 3GPP NR systemhas been designed to provide a plurality of logical networks in a singlephysical system and support services with various requirements (e.g.,eMBB, mMTC, URLLC, etc.) by changing a transmission time interval (TTI)and/or an OFDM numerology (e.g., OFDM symbol duration, SCS, and so on).In recent years, data traffic has significantly increased with theadvent of smart devices. Thus, the 3GPP NR system has also consideredthe use of an unlicensed band for cellular communication as inlicense-assisted access (LAA) of the legacy 3GPP LTE system. However,unlike the LAA, a NR cell in the unlicensed-band (NR U-cell) aims tosupport a stand-alone operation. For example, PUCCH, PUSCH, and/or PRACHtransmission may be supported in the NR UCell.

FIG. 11 illustrates an exemplary wireless communication systemsupporting an unlicensed band applicable to the present disclosure.

In the following description, a cell operating in a licensed band(L-band) is defined as an L-cell, and a carrier of the L-cell is definedas a (DL/UL) LCC. A cell operating in an unlicensed band (U-band) isdefined as a U-cell, and a carrier of the U-cell is defined as a (DL/UL)UCC. The carrier/carrier-frequency of a cell may refer to the operatingfrequency (e.g., center frequency) of the cell. A cell/carrier (e.g.,CC) is commonly called a cell.

When carrier aggregation (CA) is supported, one UE may use a pluralityof aggregated cells/carriers to exchange a signal with the BS. When oneUE is configured with a plurality of CCs, one CC may be set to a primaryCC (PCC), and the remaining CCs may be set to secondary CCs (SCCs).Specific control information/channels (e.g., CSS PDCCH, PUCCH) may betransmitted and received only on the PCC. Data may be transmitted andreceived on the PCC/SCC. FIG. 9(a) shows a case in which the UE and BSexchange signals on both the LCC and UCC (non-stand-alone (NSA) mode).In this case, the LCC and UCC may be set to the PCC and SCC,respectively. When the UE is configured with a plurality of LCCs, onespecific LCC may be set to the PCC, and the remaining LCCs may be set tothe SCC. FIG. 9(a) corresponds to the LAA of the 3GPP LTE system. FIG.9(b) shows a case in which the UE and BS exchange signals on one or moreUCCs with no LCC (stand-alone (SA) mode). In this case, one of the UCCsmay be set to the PCC, and the remaining UCCs may be set to the SCC.Both the NSA mode and SA mode may be supported in the U-band of the 3GPPNR system.

FIG. 12 illustrates an exemplary method of occupying resources in anunlicensed band. According to regional regulations for the U-band, acommunication node in the U-band needs to determine whether acorresponding channel is used by other communication node(s) beforetransmitting a signal. Specifically, the communication node may performcarrier sensing (CS) before transmitting the signal so as to checkwhether the other communication node(s) perform signal transmission.When the other communication node(s) perform no signal transmission, itis said that clear channel assessment (CCA) is confirmed. When a CCAthreshold is predefined or configured by higher layer signaling (e.g.,RRC signaling), if the detected channel energy is higher than the CCAthreshold, the communication node may determine that the channel isbusy. Otherwise, the communication node may determine that the channelis idle. When it is determined that the channel is idle, thecommunication node may start the signal transmission in the UCell. TheWi-Fi standard (802.11ac) specifies a CCA threshold of 62 dBm fornon-Wi-Fi signals and a CCA threshold of −82 dBm for Wi-Fi signals. Thesires of processes described above may be referred to asListen-Before-Talk (LBT) or a channel access procedure (CAP). The LBTmay be interchangeably used with the CAP.

In Europe, two LBT operations are defined: frame based equipment (FBE)and load based equipment (LBE). In FBE, one fixed frame is made up of achannel occupancy time (e.g., 1 to 10 ms), which is a time period duringwhich once a communication node succeeds in channel access, thecommunication node may continue transmission, and an idle periodcorresponding to at least 5% of the channel occupancy time, and CCA isdefined as an operation of observing a channel during a CCA slot (atleast 20 us) at the end of the idle period. The communication nodeperforms CCA periodically on a fixed frame basis. When the channel isunoccupied, the communication node transmits during the channeloccupancy time, whereas when the channel is occupied, the communicationnode defers the transmission and waits until a CCA slot in the nextperiod.

In LBE, the communication node may set q∈{4, 5, . . . , 32} and thenperform CCA for one CCA slot. When the channel is unoccupied in thefirst CCA slot, the communication node may secure a time period of up to(13/32)q ms and transmit data in the time period. When the channel isoccupied in the first CCA slot, the communication node randomly selectsN∈{1, 2, . . . , q}, stores the selected value as an initial value, andthen senses a channel state on a CCA slot basis. Each time the channelis unoccupied in a CCA slot, the communication node decrements thestored counter value by 1. When the counter value reaches 0, thecommunication node may secure a time period of up to (13/32)q ms andtransmit data.

To transmit a DL signal in an unlicensed band, the BS may perform one ofthe following unlicensed band access procedures (e.g., CAPs).

(1) First DL CAP Method

FIG. 13 is a flowchart illustrating DL CAP for DL signal transmission inan unlicensed band, performed by a BS.

For DL signal transmission (e.g., transmission of a DL signal such as aPDSCH/PDCCH/enhanced PDCCH (EPDCCH)), the BS may initiate a CAP (S1110).The BS may randomly select a backoff counter N within a contentionwindow (CW) according to step 1. N is set to an initial value N_(init)(S1120). N_(init) is a random value selected from the values between 0and CW_(p). Subsequently, when the backoff counter value N is 0according to step 4 (S1130; Y), the BS terminates the CAP (S1132). TheBS may then perform a Tx burst transmission including transmission of aPDSCF1/PDCCH/EPDCCH (S1134). On the contrary, when the backoff countervalue N is not 0 (S1130; N), the BS decrements the backoff counter valueby 1 according to step 2 (S1140). Subsequently, the BS checks whetherthe channel of U-cells) is idle (S1150). If the channel is idle (S1150;Y), the BS determines whether the backoff counter value is 0 (S1130), Onthe contrary, when the channel is not idle, that is, the channel is busy(S1150; N), the BS determines whether the channel is idle during alonger deter duration Id (25 usec or longer) than a slot duration (e.g.,9 usec) according to step 5 (S1160). If the channel is idle during thedefer duration (S1170; Y), the BS may resume the CAP. The defer durationmay include a 16-usec duration and the immediately following m_(p)consecutive slot durations (e.g., each being 9 usec). On the contrary,if the channel is busy during the defer duration (S1170; N), the BSre-checks whether the channel of the U-cell(s) is idle during a newdefer duration by performing step S1160 again.

Table 6 illustrates that m_(p), a minimum CW, a maximum CW, a maximumchannel occupancy time (MCOT), and an allowed CW size applied to a CAPvary according to channel access priority classes.

TABLE 6 Channel Access Priority Class (p) m_(p) CW_(min, p) CW_(max, p)T_(mcotp) allowed CW_(p) sizes 1 1  3  7 2 ms (3, 7) 2 1  7  15 3 ms (7, 15) 3 3 15  63 8 or 10 ms (15, 31, 63) 4 7 15 1023 8 or 10 ms (15,31, 63, 127, 255, 511, 1023)

A CW size applied to the first DL CAP may be determined in variousmethods. For example, the CW size may be adjusted based on theprobability of HARQ-ACK values corresponding to PDSCH transmission(s)within a predetermined time period (e.g., a reference TU) beingdetermined as NACK. In the case where the BS performs a DL transmissionincluding a PDSCH that is associated with a channel access priorityclass p on a carrier, if the probability z of HARQ-ACK valuescorresponding to PDSCH transmission(s) in reference subframe k (orreference slot k) being determined as NACK is at least 80%, the BSincreases a CW value set for each priority class to the next higherallowed value. Alternatively, the BS maintains the CW value set for eachpriority class to be an initial value. A reference subframe (orreference slot) may be defined as the starting subframe (or slot) of themost recent transmission on the carrier made by the BS, for which atleast some HARQ-ACK feedback is expected to be available.

(2) Second DL CAP Method

The BS may perform a DL signal transmission (e.g., a signal transmissionincluding a discovery signal transmission, without a PDSCH) in anunlicensed band according to the second DL CAP method described below.

When the signal transmission duration of the BS is equal to or less than1 ms, the BS may transmit a DL signal (e.g., a signal including adiscovery signal without a PDSCH) in the unlicensed band immediatelyafter sensing the channel to be idle for at least a sensing durationT_(drs)=25 us. T_(drs) includes a duration T_(f) (=16 us) following onesensing slot duration T_(sl) (=9 us).

(3) Third DL CAP Method

The BS may perform the following CAPs for DL signal transmission onmultiple carriers in an unlicensed band.

1) Type A: The BS performs a CAP for multiple carriers based on acounter N defined for each carrier (a counter N considered in a CAP) andperforms a DL signal transmission based on the CAP.

-   -   Type A1: The counter N for each carrier is determined        independently, and a DL signal is transmitted on each carrier        based on the counter N for the carrier.    -   Type A2: The counter N of a carrier with a largest CW size is        set for each carrier, and a DL signal is transmitted on each        carrier based on the counter N for the carrier.

2) Type B: The BS performs a CAP based on a counter N only for aspecific one of a plurality of carriers and performs a DL signaltransmission by checking whether the channels of the other carriers areidle before a signal transmission on the specific carrier.

-   -   Type B1: A single CW size is defined for a plurality of        carriers, and the BS uses the single CW size in a CAP based on        the counter N for a specific carrier.    -   Type B2: A CW size is defined for each carrier, and the largest        of the CW sizes is used in determining N_(init) for a specific        carrier.

For a UL signal transmission in the unlicensed band, the UE performs acontention-based CAP. For example, the UE may perform a Type 1 CAP or aType 2 CAP for UL signal transmission in the U-band. In general, the UEmay perform a CAP configured/indicated by the BS (e.g., Type 1 CAP orType 2 CAP) for the UL signal transmission.

(1) Type 1 UL CAP Method

FIG. 14 is a flowchart illustrating UE's Type 1 CAP operation for ULsignal transmission.

To transmit a signal in the U-band, the UE may initiate a CAP (S1210).The UE may randomly select a backoff counter N within a contentionwindow (CW) according to step 1. In this case, N is set to an initialvalue N_(init) (S1220). N_(init) may have a random value between 0 andCW_(p). If it is determined according to step 4 that the backoff countervalue (N) is 0 (Y in S1230), the UE terminates the CAP (S1232). Then,the UE may perform Tx burst transmission (S1234). If the backoff countervalue is non-zero (N in S1230), the UE decreases the backoff countervalue by 1 according to step 2 (S1240). The UE checks whether thechannel of U-cell(s) is idle (S1250). If the channel is idle (Y inS1250), the UE checks whether the backoff counter value is 0 (S1230). Onthe contrary, if the channel is not idle in S1250, that is, if thechannel is busy (N in S1250), the UE checks whether the correspondingchannel is idle for a defer duration T_(d) (longer than or equal to 25usec), which is longer than a slot duration (e.g., 9 usec), according tostep 5 (S1260). If the channel is idle for the defer duration (Y inS1270), the UE may resume the CAP. Here, the defer duration may includea duration of 16 usec and m_(p) consecutive slot durations (e.g., 9usec), which immediately follows the duration of 16 usec. If the channelis busy for the defer duration (N in S1270), the UE performs step S1260again to check whether the channel is idle for a new defer duration.

Table 7 shows that the values of m_(p), a minimum CW, a maximum CW, amaximum channel occupancy time (MCOT), and allowed CW sizes, which areapplied to the CAP, vary depending on channel access priority classes.

TABLE 7 Channel Access Priority Class (p) m_(p) CW_(min, p) CW_(max, p)T_(mcotp) allowed CW_(p) sizes 1 2  3   7 2 ms (3, 7) 2 2  7  15 4 ms (7, 15) 3 3 15 1023 6 ms or 10 ms (15, 31, 63, 127, 255, 511, 1023) 4 715 1023 6 ms or 10 ms (15, 31, 63, 127, 255, 511, 1023)

The size of a CW applied to the Type 1 UL CAP may be determined invarious ways. For example, the CW size may be adjusted depending onwhether the value of a new data indicator (NDI) for at least one HARQprocess associated with HARQ_ID_ref, which is the HARQ process ID of aUL-SCH in a predetermined time period (e.g., a reference TU), istoggled. When the UE performs signal transmission using the Type 1 CAPassociated with the channel access priority class p on a carrier, if thevalue of the NDI for the at least one HARQ process associated withHARQ_ID_ref is toggled, the UE may set CW_(p) to CW_(min, p) for everypriority class p∈{1, 2, 3, 4}. Otherwise, the UE may increase CW_(p) forevery priority class p∈{1, 2, 3, 4} to a next higher allowed value.

(2) Type 2 UL CAP Method

When the UE uses the Type 2 CAP to transmit a UL signal (including thePUSCH) in a U-band, the UE may transmit the UL signal (including thePUSCH) in the U-band immediately after sensing that the channel is idleat least for a sensing period T_(short_ul) of 25 us. T_(short_ul)includes a duration T_(f) of 16 us immediately followed by one slotduration T_(sl) of 9 us. T_(f) includes an idle slot duration T_(sl) atthe start thereof.

To support a stand-alone operation in a U-band, a UE operation oftransmitting an HARQ-ACK feedback based on a U-band PUCCH/PUSCHtransmission, in response to a DL data (e.g., PDSCH) reception may beessential. For example, a process of scheduling a DL data transmissionfor a UE in a COT occupied by LBT (CCA) and indicating to the UE totransmit an HARQ-ACK feedback for the DL data reception in the same COTby a gNB may be considered. In another example, a process of indicatingtransmission of an HARQ-ACK feedback for reception of DL datascheduled/transmitted in a specific COT, in another COT after thespecific COT because of a UE processing time required for decoding a DLdata signal and encoding an HARQ-ACK signal corresponding to the DL datasignal may also be considered.

The present disclosure proposes a method of configuring and transmittingan HARQ-ACK feedback in consideration of an LBT operation and a COTconfiguration in a U-band.

The proposed methods of the present disclosure may be applied to anoperation/process of transmitting other UCI (e.g., CSI or SR) on aPUCCH/PUSCH, not limited to an operation/process of transmitting anHARQ-ACK feedback on a PUCCH/PUSCH. Further, the proposed methods of thepresent disclosure are not limited to an LBT-based U-band operation, andmay be applied to an L-band (or U-band) operation without LBT in asimilar manner. In the following description, a band may beinterchangeably used with a CC/cell. Further, a CC/cell (index) may bereplaced with a BWP (index) configured in a CC/cell or a CC (index)-BWP(index) combination. For convenience, an HARQ-ACK is referred to as anA/N in the following description.

The terms as used herein are defined as follows.

-   -   UCI: Control information that the UE transmits on UL. UCI        includes a few types of control information (i.e., UCI types).        For example, the UCI includes HARQ-ACK (simply, A/N), SR, and        CSI.    -   PUCCH: A physical-layer UL channel for UCI transmission. For        convenience, PUCCH resources configured and/or indicated for        A/N, SR, and CSI transmissions by the BS are referred to as A/N        PUCCH resources, SR PUCCH resources, and CSI PUCCH resources,        respectively.    -   UL grant DCI: DCI for a UL grant. For example, UL grant DCI is        DCI format 0_0 or DCI format 0_1, transmitted on a PDCCH.    -   DL grant DCI: DCI for a DL grant. For example, DL grant DCI is        DCI format 1_0 or DCI format 1_1, transmitted on a PDCCH.    -   PUSCH: A physical-layer UL channel for UL data transmission.    -   Slot: A basic time unit (TU) or time interval for data        scheduling. A slot includes a plurality of symbols. A symbol may        be an OFDM-based symbol (e.g., CP-OFDM symbol or DFT-s-OFDM        symbol). In the present disclosure, the terms symbol, OFDM-based        symbol, OFDM symbol, CP-OFDM symbol, and DFT-s-OFDM symbol are        interchangeably used.    -   LBT for channel X: LBT performed to determine whether channel X        is available for transmission. For example, a CAP (e.g., see        FIG. 14) may be performed before the start of transmission of        channel X.    -   LBT in/for symbol X: LBT performed to determine whether symbol X        is available for transmission. For example, a CAP (e.g., see        FIG. 14) may be performed in symbol(s) previous to symbol X.

Unless contradicting each other, each of the proposed methods describedbelow may be applied in combination with any of the other proposedmethods.

(1) Basic Operation Methods

Basic operation methods for A/N feedback configuration/transmission asproposed in the present disclosure will be described below.

1) Timing-Based A/N Feedback Method (for Convenience, Referred to ast-A/N Scheme)

After preconfiguring a plurality of candidate HARQ timings (e.g.,PDSCH-to-A/N timings) by RRC signaling, the BS may indicate one of thecandidate HARQ timings to the UE by (DL grant) DCI. The UE may thentransmit an A/N feedback for receptions of (a plurality of) PDSCHs in aplurality of slots corresponding to the total candidate HARQ timing setat the indicated HARQ timing (for convenience, this A/N feedbackconfiguration/transmission method is referred to as a ‘type-1 A/Ncodebook). The set of the plurality of slots corresponding to the totalcandidate HARQ timing set may be defined as a ‘bundling window’corresponding to the indicated HARQ timing.

In addition to an indication of one HARQ timing, the DCI may furtherinclude a counter-downlink assignment index (DAI) and/or a total-DAI.The counter-DAI may indicate the scheduled number of a PDSCHcorresponding to the (DL grant) DCI. The total-DAI may indicate thetotal number of PDSCHs scheduled up to the current time. In this case,the UE may transmit A/Ns for PDSCHs corresponding to counter-DAI valuesfrom an initial counter-DAI value to the last (received) total-DAI valueat an indicated HARQ timing (for convenience, this A/N feedbackconfiguration/transmission method is referred to as a ‘type-2 A/Ncodebook).

2) Pooling-Based A/N Feedback Method (for Convenience, Referred to asp-A/N Scheme)

The BS may indicate pending of an A/N feedback transmission for acorresponding PDSCH by DL grant DCI. Subsequently, the BS may indicatetransmission of an A/N feedback for a PDSCH corresponding to total DLHARQ process IDs or some specific DL HARQ process ID(s) at a timingconfigured/indicated by a specific signal (e.g., RRC signaling or DCI)by specific DCI (e.g., DL grant DCI, UL grant DCI, or other DCI)(pooling) (for convenience, this A/N feedback configuration/transmissionis referred to as a ‘type-3 A/N codebook’).

When counter-DAI/total-DAI signaling is configured for the t-A/N scheme,A/N pooling may be defined as pooling of an A/N transmission for a PDSCHcorresponding to an HARQ process ID (indicated by pooling DCI) orpooling of an A/N transmission for at least one PDSCH corresponding to atotal-DAI value (indicated by pooling DCI).

(2) Proposed Method 1

In proposed method 1, switching between the t-A/N scheme and the p-A/Nscheme (e.g., which one between the t-A/N scheme and the p-A/N scheme isused to configure/transmit an A/N feedback) may be indicated by DL grantDCI. A/N pending or A/N pooling for the p-A/N scheme (i.e., whether theA/N feedback transmission of the UE is to be pended or pooled) isadditionally indicated by the DL grant DCI. Specifically, the followingoptions may be considered. Additionally, configuration/relatedinformation about an A/N feedback subject to pooling (e.g., a CC groupand/or HARQ process ID set for which the A/N feedback is to betransmitted, or a total-DAI) may be indicated by DL grant DCI indicatingA/N pooling in the following options.

1) Opt 1-1

The UE may identify whether an A/N feedback scheme is the t-A/N schemeor the p-A/N scheme by a 1-bit flag in DL grant DCI and interpretdifferently a specific field (e.g., A-field) in the DCI according to theindicated value of the flag. The A-field may be a new field added toindicate a specific feedback method according to a feedback scheme.Alternatively, the A-field may be some of legacy DCI fields (e.g., anHARQ-ACK transmission timing field, a DAI field, and a PDSCHscheduling-related field) to maintain a DCI size.

When the flag indicates the t-A/N scheme, the A-field may indicate oneHARQ timing (among a plurality of candidate HARQ timings).

On the contrary, when the flag indicate the p-A/N scheme, the A-fieldmay indicate whether an A/N feedback transmission is to be pended orpooled (in the latter case, a timing at which the A/N feedback subjectto pooling is to be transmitted).

When counter-DAI/total-DAI signaling is configured for the t-A/N scheme,a corresponding DAI field in (DL grant) DCI indicating A/N pooling mayindicate A/N feedback configuration/related information (e.g., a CCgroup and/or HARQ process ID set for which the A/N feedback is to betransmitted, or a total-DAI). For example, a CC group or HARQ process IDfor which the feedback is to be transmitted may be indicated by a 2-bitcounter DAI field (or a 2-bit total DAI field). In another example, acombination of a CC group and an HARQ process ID for which the feedbackis to be transmitted may be indicated by both the counter DAI field andthe total DAI field.

When A/N pending is indicated, at least a counter-DAI may be signaled,and a total-DAI may not be signaled by the (DL grant) DCI. In the lattercase, although the DCI includes the total-DAI, the total-DAI may not beused in an HARQ-ACK feedback process.

Opt 1-2

The BS may jointly indicate selection between the t-A/N scheme and thep-A/N scheme and information about the selected A/N scheme by onespecific field (A-field) in DL grant DCI. Herein, the 1-bit flag of Opt1-1 is not needed.

For example, one of {t-A/N with timing X1, t-A/N with timing X2, . . . ,A/N pending, A/N pooling in timing Y1, A/N pooling in timing Y2, . . . }may be indicated by the A-field. ‘t-A/N with timing X’ represents at-A/N-based A/N feedback transmission at timing X, and ‘AN pooling intiming Y’ represents a p-A/N-based A/N feedback transmission at timingY. Further, an A/N feedback transmission timing corresponding to A/Npooling may have one value, which may be predefined or configured by RRCsignaling. For example, when a pooling timing is fixed, the poolingtiming may include only one timing Y. In another example of a fixedpooling timing, when a plurality of values Y1, Y2, . . . , Yn areincluded, only Y1 indicates a pooling timing, whereas the other valuesY1, . . . , Yn may be used to indicate a pooling target. When DAIsignaling is configured for the t-A/N scheme, configuration/relatedinformation about an A/N subject to pooling (e.g., a CC group/HARQprocess ID or a total-DAI) may be indicated by a DAI field in DCIindicating A/N pooling (when A/N pending is indicated, at least acounter-DAI may be signaled (without signaling of a total-DAI) by DCI).

FIGS. 15 and 16 illustrate a signal transmission process according tothe present disclosure.

Referring to FIG. 15, a UE receives DL grant DCI from a BS (S1510). TheDL grant DCI may include DL scheduling information and HARQ-ACK feedbackinformation for a PDSCH. The DL scheduling information may include afirst field including related information required for the UE toconfigure payload of an HARQ-ACK feedback for the PDSCH.

The UE receives the PDSCH based on the DL scheduling information(S1520).

The UE may transmit an HARQ-ACK feedback for the PDSCH received in stepS1520 (hereinafter, referred to as first PDSCH), defer the HARQ-ACKfeedback transmission for the first PDSCH, or transmit an HARQ-ACKfeedback for a previously received second PDSCH (e.g., a previous PDSCHfor which an HARQ-ACK feedback has been pooled without beingtransmitted) (S1530).

For example, the UE receives DCI including DL scheduling information andinformation about an HARQ-ACK feedback type (S1610 and S1710) andreceives a first PDSCH based on the DCI (S1620 and S1720). When theHARQ-ACK feedback type is a first type (e.g., t-A/N), the UE transmitsan HARQ-ACK feedback for the first PDSCH (S1630). When the HARQ-ACKfeedback type is a second type (e.g., p-A/N), the UE may pend theHARQ-ACK feedback for the first PDSCH (S1730). When pooling informationis included along with a pending indication in the DCI, the UE maytransmit an HARQ-ACK feedback for a pooled second PDSCH (S1740).

According to Opt 1-1, a 1-bit flag indicating an HARQ-ACK feedback typemay be included separately in the DCI. The UE may identify whether theHARQ-ACK feedback type is the first type (e.g., t-A/N) or the secondtype (e.g., p-A/N), and determine a feedback type to which informationincluded in the first field is related, based on the identified feedbacktype. For example, when the UE identifies the HARQ-ACK feedback type asthe first type by the value of the flag, the UE may configure payload ofthe HARQ-ACK feedback for the first PDSCH based on the informationincluded in the first field (information indicated by the first field).In the case of the first type, the first field may include informationabout a transmission timing of the HARQ-ACK feedback. When the UEidentifies the HARQ-ACK feedback type as the second type, the UE maypend the HARQ-ACK feedback transmission for the first PDSCH or configureHARQ-ACK payload for the second PDSCH. In the case of the second type,the first field may include information indicating whether the HARQ-ACKfeedback for the first PDSCH is to be pended and the HARQ-ACK feedbackfor the second PDSCH is to be pooled. In the latter pooling case,information about the second PDSCH for which the HARQ-ACK is to betransmitted and a transmission timing of the HARQ-ACK may be included inthe first field.

According to Opt 1-2, the 1-bit flag is not needed. In Opt 1-2, thefirst field may include information about an HARQ-ACK feedback timing inthe case of the first type, and one of information indicating whether anHARQ-ACK feedback is to be pended and information about a PDSCH subjectto pooling (including an HARQ-ACK feedback transmission timing) in thecase of the second type. The UE may perform an HARQ-ACK feedback processsuitable for the type by checking the information included in the firstfield (or the information indicated by the first field).

According to proposed method 1 (Opt 1-1 and Opt 1-2), DL scheduling andpooling or non-pooling of a PDSCH may be indicated by the same DCI.Further, the first field may be a newly added field or a legacy DCIfield used to maintain a DCI size.

(3) Proposed Method 2

In proposed method 2, the BS may indicate switching between the t-A/Nscheme and A/N pending for application of the p-A/N scheme (e.g.,whether to apply the t-A/N scheme or to pend an A/N feedbacktransmission to apply the p-A/N scheme) by DL grant DCI (e.g., one of{t-A/N with timing X1, t-A/N with timing X2, . . . , A/N pending} may beindicated by a specific field, A-field of the DL grant DCI). Further,the BS may indicate A/N pooling for the p-A/N scheme by UL grant DCI.Specifically, the following options may be considered (hereinbelow, anA/N feedback subject to pooling is referred to as a pooled A/N).Additionally, pooled A/N feedback configuration/related information(e.g., information about a CC group and/or HARQ process ID set for whichthe A/N feedback is to be transmitted, or a total-DAI) may be indicatedby UL grant DCI indicating A/N pooling in the following options.

1) Opt 2-1

The BS may indicate a transmission timing of a pooled A/N and a PUCCHresource to be used for the A/N transmission, together with informationindicating whether A/N pooling is applied by UL grant DCI.

When the UL grant DCI indicates A/N pooling, the UL grant DCI may or maynot include PUSCH scheduling and information for the PUSCH scheduling(e.g., an RA and an MCS/TBS).

In the case where it is defined that DCI indicating A/N pooling includesPUSCH scheduling, when an indicated pooled PUCCH timing/resourceoverlaps with a s PUSCH timing/resource (on the time axis), a pooled A/Nfeedback may be piggybacked to a PUSCH. Characteristically, atiming/resource relationship between the pooled A/N and the PUSCH may beconfigured/indicated such that a PUCCH and the PUSCH are transmittedcontiguously in time and in the same resources in frequency (inconsideration of an efficient LBT operation and a power transienteffect). When DAI signaling is configured for the t-A/N scheme, a DAIfield in the UL grant DCI (indicating A/N pooling) may indicate pooledA/N configuration/related information (e.g., a CC group/HARQ process IDset, or a total-DAI).

When it is defined that DCI indicating A/N pooling does not includePUSCH scheduling, pooled A/N feedback configuration/transmission-relatedinformation (e.g., an A/N transmission timing, an A/N PUCCH resource, aCC group/HARQ process ID set, or a total-DAI) may be indicated by theremaining fields (e.g., an RA, an MCS/TBS, an HARQ process ID related toUL data transmission, and/or a new data indicator (NDI)/redundancyversion (RV)). In this case, a 1-bit flag in the UL grant DCI whetherthe UL grant DCI indicates A/N pooling without PUSCH scheduling orincludes PUSCH scheduling without A/N pooling. In another example, the1-bit flag of the UL grant DCI may indicate the presence or absence of aUL-SCH transmission. When the 1-bit flag indicates the absence of aUL-SCH transmission (and no CSI request), the UE may perform the aboveoperation, considering that A/N pooling has been indicated.

2) Opt 2-2

When A/N pooling is indicated by UL grant DCI, the UE may transmit apooled A/N feedback at a PUSCH timing/resource scheduled by the UL grantDCI.

When A/N pooling is indicated, it may be defined that a scheduledPUSCH 1) is indicated to include or not to include a UL-SCH or 2) doesnot include a UL-SCH at all. In the latter case, it may be indicated bya 1-bit flag in the UL grant DCI whether the UE is to transmit a pooledA/N without a UL-SCH (on the scheduled PUSCH) or to transmit the UL-SCHwithout A/N pooling (on the scheduled PUSCH). In another example, in thelatter case, when the 1-bit flag indicates that there is no UL-SCHtransmission (and no CSI request), the UE may perform the followingoperation, considering that A/N pooling has been indicated.

In the case where the PUSCH includes (or is indicated to include) aUL-SCH, when DAI signaling is configured for the t-A/N scheme, a UL DAIfield in the UL grant DCI (indicating A/N pooling) may indicate pooledA/N feedback configuration/related information (e.g., a CC group/HARQprocess ID, or a total-DAI).

When the PUSCH does not include (or is indicated not to include) aUL-SCH, a specific field (e.g., a field related to an HARQ process ID oran NDI/RV) in the UL grant DCI may indicate pooled A/N feedbackconfiguration/related information (e.g., a CC group/HARQ process ID, ora total-DAI).

(4) Proposed Method 3

In proposed method 3, the BS may indicate switching between the t-A/Nscheme and A/N pending for applying the p-A/N scheme (e.g., whether toapply the t-A/N scheme or to pend an A/N feedback transmission (forapplying the p-A/N scheme)) by DL grant DCI (e.g., one of {t-A/N withtiming X1, t-A/N with timing X2, . . . , A/N pending} may be indicatedby an A-field in the DL grant). Further, the A/N pooling operation forthe p-A/N scheme may be indicated by UE-common DCI (hereinafter,referred to as common DCI). Specifically, the following options may beconsidered.

Additionally, pooled A/N configuration/related information (e.g., a CCgroup/HARQ process ID, or a total-DAI) by common DCI indicating A/Npooling in the following options.

1) Opt 3-1

In a state where an A/N transmission timing and an A/N PUCCH resourcefor a pooled A/N feedback transmission are preconfigured UE-specificallyby RRC signaling, the BS may indicate only A/N pooling or non-A/Npooling for each UE by a 1-bit flag included in common DCI.

2) Opt 3-2

In a state where a plurality of combinations of {A/N transmissiontiming, A/N PUCCH resource} for a pooled A/N feedback transmission arepreconfigured UE-specifically by RRC signaling, the UE may indicate oneof the combinations of {A/N transmission timing, A/N PUCCH resource} ona UE basis by K bits (K>1) in common DCI.

3) Opt 3-3

In a state where a single value for one (e.g., X) of an A/N timing andan A/N PUCCH resource for a pooled A/N feedback transmission, and aplurality of candidates values for the other (e.g., Y) are preconfiguredUE-specifically by RRC signaling, the BS may indicate one of theplurality of candidate values for Y (as well as A/N pooling or non-A/Npooling) by L bits (L>1) in common DCI. For example, if X represents theA/N timing and Y represents the PUCCH resource, it may be said that onevalue has been set for the A/N timing and a plurality of candidates havebeen configured for the PUCCH resource.

(5) Proposed Method 4

In proposed method 4, the BS may indicate switching between the t-A/Nscheme and A/N pending for applying the p-A/N scheme (e.g., whether toapply the t-A/N scheme or to pend an A/N feedback transmission (forapplying the p-A/N scheme)) by DL grant DCI (e.g., first DCI) includingPDSCH scheduling and information for the PDSCH scheduling (e.g. an RAand an MCS/TBS) (e.g., one of {t-A/N with timing X1, t-A/N with timingX2, . . . , A/N pending} may be indicated by a specific field, A-fieldin the first DCI). The A/N pooling operation for the p-A/N scheme may beindicated by DL grant DCI (e.g., second DCI) that does not include PDSCHscheduling.

Specifically, the BS may indicate a transmission timing and an A/N PUCCHresource of a pooled A/N feedback transmission as well as A/N pooling(or non-A/N pooling) by DL grant DCI (e.g., the second DCI). When A/Npooling is indicated by DCI (e.g., the second DCI), PDSCH scheduling isnot included in the DCI. Therefore, pooled A/N feedbackconfiguration/transmission-related information (e.g., an A/Ntransmission timing, an A/N PUCCH resource, a CC group/HARQ process IDset, or a total-DAI) may be indicated by a remaining field of the DLgrant DCI (e.g., the second DCI) (e.g., an RA, an MCS/TBS, an HARQprocess ID, or an NDI/RV).

With reference made to FIG. 17, for example, the UE may receive firstDCI from the BS (S1810). The first DCI may include DL schedulinginformation for a first PDSCH, and may further include information aboutan HARQ-ACK feedback type (specifically, information indicating whetherthe HARQ-ACK feedback type is the t-A/N type or the p-A/N type, and inthe case of the p-A/N type, indicating HARQ-ACK feedback pending for thefirst PDSCH). The UE may receive second DCI from the BS (S1820). Thatis, when the first DCI indicates HARQ-ACK feedback pending for the p-A/Ntype, the UE may attempt to detect the second DCI. For example, thesecond DCI may have the same size and RNTI as those of general DL grantDCI. Because the second DCI does not include PDSCH schedulinginformation, information about whether pooling is performed, aconfiguration of the payload of a pooled HARQ-ACK feedback, andresources for transmission of the pooled HARQ-ACK feedback may beindicated by a combination of specific fields related to PDSCHscheduling. In another example, the second DCI may have a different sizeand RNTI from those of the general DL grant DCI. To mitigate the PDCCHblind decoding overhead of the UE, the monitoring timing/interval of thesecond DCI may be limited based on a time at which the first DCI hasbeen detected. The UE receives the first PDSCH based on the first DCI(S1830). As the first DCI indicates HARQ-ACK feedback pending for thep-A/N, the UE pends the transmission of the HARQ-ACK for the first PDSCH(S1840). Subsequently, the UE may transmit an HARQ-ACK feedback for apreviously received second PDSCH based on pooled HARQ-ACK feedbackinformation indicated by the second DCI (S1850). According to FIG. 17,the BS may transmit information about HARQ-ACK feedback pooling in DCIdifferent from DCI carrying DL scheduling information. Because the DCIincluding the information about HARQ-ACK feedback pooling does notinclude DL scheduling information, the BS may provide informationrelated to the configuration and transmission of a pooled HARQ-ACKfeedback to the UE by a legacy DCI field used for DL scheduling.

In another example, when a plurality of bits included in an RA field ofDL grant DCI indicate an invalid resource allocation (e.g., when all ofthe bits of the RA field indicate ‘1’ in a state in which an (RB-basedor RBG-based) resource indication value (MV) resource allocation schemeis indicated, or when all of the bits of the RA field indicate ‘0’ in astate in which an (RB-based or RBG-based) bitmap resource allocationscheme is indicated), upon detection of the DCI, the UE may operate,considering/interpreting that A/N pooling has been indicated. In thiscase, pooled A/N configuration/transmission-related information (e.g.,an A/N transmission timing, an A/N PUCCH resource, a CC group/HARQprocess ID set, or a total-DAI) may be indicated by the remaining fieldsof the DCI (e.g., an A/N timing indicator field, an A/N PUCCH resourceallocation field, an MCS/TBS, an HARQ process ID, and an NDI/RV).

The above method may also be applied in the same manner, with DL grantDCI replaced with UL grant DCI.

When a valid resource allocation is indicated by the RA field of theDCI, the UE may operate, considering/interpreting that switching betweenthe t-A/N scheme and A/N pending for application of the p-A/N scheme(e.g., application of the t-A/N scheme or pending of an A/N feedbacktransmission (for applying the p-A/N scheme)) has been indicated(simultaneously with PDSCH transmission scheduling) by the DCI.

(6) Additional Proposed Method 1

When an A/N feedback is configured based on the t-A/N scheme, an HARQtiming set (and a CC group) for which an A/N feedback is to betransmitted (among total candidate HARQ timings) may be indicated by (DLgrant) DCI, to dynamically adapt/reduce an A/N payload size.Alternatively, in a state where an HARQ timing set (and a CC group) (forwhich an A/N feedback is to be transmitted) is preconfigured for eachPUCCH resource (set) by RRC signaling, the BS may indicate a specificPUCCH resource (set) by (DL grant) DCI, and the UE mayconfigure/transmit an A/N feedback corresponding to an HARQ timing set(and a CC group) configured for the specific PUCCH resource (set).

Further, to dynamically adapt/reduce an A/N payload size when an A/Nfeedback is configured based on the t-A/N scheme configured with DAIsignaling is configured, a total-DAI value (for which an A/N feedback isto be transmitted) may be preconfigured for each PUCCH resource (set) byRRC signaling. In this state, when the BS indicates a specific PUCCHresource (set) by (DL grant) DCI, the UE may configure/transmit an A/Nfeedback corresponding to a total-DAI configured for the specific PUCCHresource (set).

Further, to dynamically adapt/reduce an A/N payload size when an A/Nfeedback is configured based on the p-A/N scheme is configured, the BSmay indicate an HARQ ID set (and a CC group) for which an A/N feedbackis to be transmitted (among total HARQ process IDs) by DCI indicatingA/N pooling. Alternatively, in a state where an HARQ ID set (and a CCgroup) (for which an A/N feedback is to be transmitted) may bepreconfigured for each PUCCH resource (set) by RRC signaling, when theBS indicates a specific PUCCH resource (set) by DCI indicating A/Npooling, the UE may configure/transmit an A/N feedback corresponding toan HARQ ID set (and a CC group) for the indicated specific PUCCHresource (set).

(7) Additional Proposed Method 2

When DL grant DCI indicates pending of an A/N feedback to a UE, whichhas been configured with a specific (e.g., type-1) A/N codebook schemebased on the t-A/N scheme, 1) an operation of transmitting the pendedA/N in the form of a type-3 A/N codebook (by the UE) by indicating A/Npooling separately by specific DCI or 2) an operation of configuring anA/N by adding a pended A/N to a type-1 A/N codebook transmitted at anHARQ timing indicated by another DL grant DCI, without A/N pooling(e.g., an operation of configuring single A/N payload by adding a pendedA/N to a corresponding type-1 A/N codebook) may be considered.

For example, transmission of PDSCH #1 in slot #n and transmission of anA/N feedback corresponding to PDSCH #1 in slot #(n+K1) may be indicatedby a specific DL grant DCI. Transmission of PDSCH #2 in slot #(n+L1) andpending of an A/N feedback corresponding to PDSCH #2 may be indicated byanother DL grant DCI. Herein, K1>L1. Transmission of PDSCH #3 in slot#(n+L2) and transmission of an A/N feedback corresponding to PDSCH #3 inslot #(n+K2) may be indicated by a third DL grant DCI. Herein, K2>K1 andL2>L1. A/N payload transmitted in slot #(n+K1) may be configured withA/N information for PDSCH receptions (including PDSCH #1) within abundling window corresponding to slot #(n+K1). A/N payload transmittedin slot #(n+K2) may be configured with the pended A/N (for PDSCH #2) inaddition to A/N information for PDSCH receptions including PDSCH #3within a bundling window corresponding to slot #(n+K2).

When A/N payload is configured/transmitted by adding a pended A/N to atype-1 A/N codebook, 1) the total size of the pended A/N information/thetotal number of the pended A/N bits and 2) the mapping order between thepended A/N information/bits in the A/N payload should be matched betweenthe UE and the BS. A probable mismatch between the UE and the BSregarding the number/mapping order of the pended A/Ns in the A/N payloadcauses serious ACK/NACK (e.g., NACK-to-ACK) errors as well asdegradation of UCI decoding performance. Therefore, unnecessary PDSCHretransmission overhead and long latency may result. To prevent theproblem, a (maximum) allowed size/number of pended A/N information/bits(e.g., P bits) to be added to a type-1 A/N codebook may be configuredfor the UE by RRC signaling (from the BS). The UE may configure finalA/N payload by adding P bits to A/N payload based on a type-1 A/Ncodebook, regardless of the presence or absence of an actually pendedA/N. In another method, the BS may indicate to the UE whether there is apending A/N (or P bits are to be added) by a specific (e.g., 1-bit)field in DCI (e.g., DL grant). The UE may configure final A/N payload byadding or not adding P bits to A/N payload based on a type-1 A/Ncodebook according to the information indicated by the specific field.In another method, a plurality of (different) candidates (including 0)for the number P of bits for the pended A/N may be configured for theUE. One of the candidates may be indicated by a specific field in DCI(e.g., a DL grant). The UE may configure final A/N payload by adding thenumber of bits corresponding to the indicated value to a type-1 A/Ncodebook.

Additionally, in order to match the mapping order of pended A/Ninformation/bits in A/N payload between the BS and the UE, thetransmission/scheduling order (e.g., counter value) of a PDCCH/PDSCHcorresponding to an indicated A/N pending (among total PDCCHs/PDSCHs forwhich the A/N pending is indicated) may be transmitted by a specificfield in DCI (e.g., a DL grant) indicating A/N feedback pending. The UEmay configure final A/N payload by adding pended A/N bitsconfigured/mapped according to the order of the counter value (to thetype-1 A/N codebook). In this case, the field indicating the countervalue in the DCI (e.g., DL grant) may be determined/considered as afield (e.g., a PUCCH resource indicator (PRI) field) for allocatingPUCCH resources (to be used for the A/N feedback transmission). Thetype-1 A/N codebook may be first mapped to a low bit index part startingfrom a most significant bit (MSB), followed by mapping of the pended A/Ninformation (to a high bit index part) in the final A/N payload.

Additionally, to prevent an A/N payload mismatch between the UE and theBS, a timing available for transmission of the pended A/N may beconfigured/set (such that the A/N payload is added to a type-1 A/Ncodebook and transmitted at the same UL timing). Specifically, when anA/N feedback pending operation is indicated for a PDSCH transmitted inslot #n by DCI (e.g., a DL grant) transmitted in slot #n, it may beconfigured/indicated that the pended A/N is transmitted only on a PUCCH(PUSCH) (carrying a type-a A/N codebook) transmitted at a timingincluding/after slot #(n+T) (and/or a timing including/after slot#(n+T+F)). Additionally, when a slot in which the PDSCH corresponding tothe pended A/N has been received coincides with slot #X included in abundling window corresponding to an A/N transmission timing indicated byany DCI (e.g., a DL grant), the UE may configure a type-1 A/N codebookfor the bundling window by mapping the pended A/N information/bits toA/N bits corresponding to slot #X.

The above-described various embodiments of the present disclosure may becombined with the above-described network initial access process and/ordiscontinuous reception (DRX) operation to constitute other variousembodiments of the present disclosure, which is obvious to those skilledin the art.

Various descriptions, functions, procedures, proposals, methods, and/oroperational flowcharts of the present disclosure may be applied to, butnot limited to, various fields requiring wirelesscommunication/connection (e.g., 5G) between devices.

It will be described in more detail with reference to the drawings. Inthe following drawings/descriptions, like reference numerals denote thesame or corresponding hardware blocks, software blocks, or functionalblocks, unless otherwise indicated.

FIG. 18 illustrates a communication system 1 applied to the presentdisclosure.

Referring to FIG. 18, the communication system 1 applied to the presentdisclosure includes wireless devices, BSs, and a network. A wirelessdevice is a device performing communication using radio accesstechnology (RAT) (e.g., 5G NR (or New RAT) or LTE), also referred to asa communication/radio/5G device. The wireless devices may include, notlimited to, a robot 100 a, vehicles 100 b-1 and 100 b-2, an extendedreality (XR) device 100 c, a hand-held device 100 d, a home appliance100 e, an IoT device 100 f, and an artificial intelligence (AI)device/server 400. For example, the vehicles may include a vehiclehaving a wireless communication function, an autonomous driving vehicle,and a vehicle capable of vehicle-to-vehicle (V2V) communication. Herein,the vehicles may include an unmanned aerial vehicle (UAV) (e.g., adrone). The XR device may include an augmented reality (AR)/virtualreality (VR)/mixed reality (MR) device and may be implemented in theform of a head-mounted device (HMD), a head-up display (HUD) mounted ina vehicle, a television (TV), a smartphone, a computer, a wearabledevice, a home appliance, a digital signage, a vehicle, a robot, and soon. The hand-held device may include a smartphone, a smart pad, awearable device (e.g., a smart watch or smart glasses), and a computer(e.g., a laptop). The home appliance may include a TV, a refrigerator, awashing machine, and so on. The IoT device may include a sensor, a smartmeter, and so on. For example, the BSs and the network may beimplemented as wireless devices, and a specific wireless device 200 amay operate as a BS/network node for other wireless devices.

The wireless devices 100 a to 100 f may be connected to the network 300via the BSs 200. An AI technology may be applied to the wireless devices100 a to 100 f, and the wireless devices 100 a to 100 f may be connectedto the AI server 400 via the network 300. The network 300 may beconfigured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g.,NR) network. Although the wireless devices 100 a to 100 f maycommunicate with each other through the BSs 200/network 300, thewireless devices 100 a to 100 f may perform direct communication (e.g.,sidelink communication) with each other without intervention of theBSs/network. For example, the vehicles 100 b-1 and 100 b-2 may performdirect communication (e.g. V2V/vehicle-to-everything (V2X)communication). The IoT device (e.g., a sensor) may perform directcommunication with other IoT devices (e.g., sensors) or other wirelessdevices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b, and 150 c may beestablished between the wireless devices 100 a to 100 f/BS 200 andbetween the BSs 200. Herein, the wireless communication/connections maybe established through various RATs (e.g., 5G NR) such as UL/DLcommunication 150 a, sidelink communication 150 b (or, D2Dcommunication), or inter-BS communication (e.g. relay or integratedaccess backhaul (IAB)). Wireless signals may be transmitted and receivedbetween the wireless devices, between the wireless devices and the BSs,and between the BSs through the wireless communication/connections 150a, 150 b, and 150 c. For example, signals may be transmitted and receivedon various physical channels through the wirelesscommunication/connections 150 a, 150 b and 150 c. To this end, at leasta part of various configuration information configuring processes,various signal processing processes (e.g., channel encoding/decoding,modulation/demodulation, and resource mapping/demapping), and resourceallocation processes, for transmitting/receiving wireless signals, maybe performed based on the various proposals of the present disclosure.

FIG. 19 illustrates wireless devices applicable to the presentdisclosure.

Referring to FIG. 19, a first wireless device 100 and a second wirelessdevice 200 may transmit wireless signals through a variety of RATs(e.g., LTE and NR). {The first wireless device 100 and the secondwireless device 200} may correspond to {the wireless device 100 x andthe BS 200} and/or {the wireless device 100 x and the wireless device100 x} of FIG. 18.

The first wireless device 100 may include one or more processors 102 andone or more memories 104, and further include one or more transceivers106 and/or one or more antennas 108. The processor(s) 102 may controlthe memory(s) 104 and/or the transceiver(s) 106 and may be configured toimplement the descriptions, functions, procedures, proposals, methods,and/or operation flowcharts disclosed in this document. For example, theprocessor(s) 102 may process information in the memory(s) 104 togenerate first information/signals and then transmit wireless signalsincluding the first information/signals through the transceiver(s) 106.The processor(s) 102 may receive wireless signals including secondinformation/signals through the transceiver(s) 106 and then storeinformation obtained by processing the second information/signals in thememory(s) 104. The memory(s) 104 may be connected to the processor(s)102 and may store various pieces of information related to operations ofthe processor(s) 102. For example, the memory(s) 104 may store softwarecode including instructions for performing all or a part of processescontrolled by the processor(s) 102 or for performing the descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document. The processor(s) 102 and the memory(s) 104may be a part of a communication modem/circuit/chip designed toimplement RAT (e.g., LTE or NR). The transceiver(s) 106 may be connectedto the processor(s) 102 and transmit and/or receive wireless signalsthrough the one or more antennas 108. Each of the transceiver(s) 106 mayinclude a transmitter and/or a receiver. The transceiver(s) 106 may beinterchangeably used with radio frequency (RF) unit(s). In the presentdisclosure, the wireless device may be a communicationmodem/circuit/chip.

The second wireless device 200 may include one or more processors 202and one or more memories 204, and further include one or moretransceivers 206 and/or one or more antennas 208. The processor(s) 202may control the memory(s) 204 and/or the transceiver(s) 206 and may beconfigured to implement the descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument. For example, the processor(s) 202 may process information inthe memory(s) 204 to generate third information/signals and thentransmit wireless signals including the third information/signalsthrough the transceiver(s) 206. The processor(s) 202 may receivewireless signals including fourth information/signals through thetransceiver(s) 106 and then store information obtained by processing thefourth information/signals in the memory(s) 204. The memory(s) 204 maybe connected to the processor(s) 202 and store various pieces ofinformation related to operations of the processor(s) 202. For example,the memory(s) 204 may store software code including instructions forperforming all or a part of processes controlled by the processor(s) 202or for performing the descriptions, functions, procedures, proposals,methods, and/or operation flowcharts disclosed in this document. Theprocessor(s) 202 and the memory(s) 204 may be a part of a communicationmodem/circuit/chip designed to implement RAT (e.g., LTE or NR). Thetransceiver(s) 206 may be connected to the processor(s) 202 and transmitand/or receive wireless signals through the one or more antennas 208.Each of the transceiver(s) 206 may include a transmitter and/or areceiver. The transceiver(s) 206 may be interchangeably used with RFunit(s). In the present disclosure, the wireless device may be acommunication modem/circuit/chip.

Now, hardware elements of the wireless devices 100 and 200 will bedescribed in greater detail. One or more protocol layers may beimplemented by, not limited to, one or more processors 102 and 202. Forexample, the one or more processors 102 and 202 may implement one ormore layers (e.g., functional layers such as physical (PHY), mediumaccess control (MAC), radio link control (RLC), packet data convergenceprotocol (PDCP), RRC, and service data adaptation protocol (SDAP)). Theone or more processors 102 and 202 may generate one or more protocoldata units (PDUs) and/or one or more service data Units (SDUs) accordingto the descriptions, functions, procedures, proposals, methods, and/oroperation flowcharts disclosed in this document. The one or moreprocessors 102 and 202 may generate messages, control information, data,or information according to the descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument and provide the messages, control information, data, orinformation to one or more transceivers 106 and 206. The one or moreprocessors 102 and 202 may generate signals (e.g., baseband signals)including PDUs, SDUs, messages, control information, data, orinformation according to the descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument and provide the generated signals to the one or moretransceivers 106 and 206. The one or more processors 102 and 202 mayreceive the signals (e.g., baseband signals) from the one or moretransceivers 106 and 206 and acquire the PDUs, SDUs, messages, controlinformation, data, or information according to the descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document.

The one or more processors 102 and 202 may be referred to ascontrollers, microcontrollers, microprocessors, or microcomputers. Theone or more processors 102 and 202 may be implemented by hardware,firmware, software, or a combination thereof. For example, one or moreapplication specific integrated circuits (ASICs), one or more digitalsignal processors (DSPs), one or more digital signal processing devices(DSPDs), one or more programmable logic devices (PLDs), or one or morefield programmable gate arrays (FPGAs) may be included in the one ormore processors 102 and 202. The descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument may be implemented using firmware or software, and the firmwareor software may be configured to include the modules, procedures, orfunctions. Firmware or software configured to perform the descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document may be included in the one or more processors102 and 202 or may be stored in the one or more memories 104 and 204 andexecuted by the one or more processors 102 and 202. The descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document may be implemented using firmware or softwarein the form of code, an instruction, and/or a set of instructions.

The one or more memories 104 and 204 may be connected to the one or moreprocessors 102 and 202 and store various types of data, signals,messages, information, programs, code, instructions, and/or commands.The one or more memories 104 and 204 may be configured to includeread-only memories (ROMs), random access memories (RAMs), electricallyerasable programmable read-only memories (EPROMs), flash memories, harddrives, registers, cash memories, computer-readable storage media,and/or combinations thereof. The one or more memories 104 and 204 may belocated at the interior and/or exterior of the one or more processors102 and 202. The one or more memories 104 and 204 may be connected tothe one or more processors 102 and 202 through various technologies suchas wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, controlinformation, and/or wireless signals/channels, mentioned in the methodsand/or operation flowcharts of this document, to one or more otherdevices. The one or more transceivers 106 and 206 may receive user data,control information, and/or wireless signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperation flowcharts disclosed in this document, from one or more otherdevices. For example, the one or more transceivers 106 and 206 may beconnected to the one or more processors 102 and 202 and transmit andreceive wireless signals. For example, the one or more processors 102and 202 may perform control so that the one or more transceivers 106 and206 may transmit user data, control information, or wireless signals toone or more other devices. The one or more processors 102 and 202 mayperform control so that the one or more transceivers 106 and 206 mayreceive user data, control information, or wireless signals from one ormore other devices. The one or more transceivers 106 and 206 may beconnected to the one or more antennas 108 and 208 and the one or moretransceivers 106 and 206 may be configured to transmit and receive userdata, control information, and/or wireless signals/channels, mentionedin the descriptions, functions, procedures, proposals, methods, and/oroperation flowcharts disclosed in this document, through the one or moreantennas 108 and 208. In this document, the one or more antennas may bea plurality of physical antennas or a plurality of logical antennas(e.g., antenna ports). The one or more transceivers 106 and 206 mayconvert received wireless signals/channels from RF band signals intobaseband signals in order to process received user data, controlinformation, and wireless signals/channels using the one or moreprocessors 102 and 202. The one or more transceivers 106 and 206 mayconvert the user data, control information, and wirelesssignals/channels processed using the one or more processors 102 and 202from the baseband signals into the RF band signals. To this end, the oneor more transceivers 106 and 206 may include (analog) oscillators and/orfilters.

FIG. 20 illustrates another example of a wireless device applied to thepresent disclosure. The wireless device may be implemented in variousforms according to a use case/service (refer to FIG. 18).

Referring to FIG. 20, wireless devices 100 and 200 may correspond to thewireless devices 100 and 200 of FIG. 18 and may be configured to includevarious elements, components, units/portions, and/or modules. Forexample, each of the wireless devices 100 and 200 may include acommunication unit 110, a control unit 120, a memory unit 130, andadditional components 140. The communication unit 110 may include acommunication circuit 112 and transceiver(s) 114. For example, thecommunication circuit 112 may include the one or more processors 102 and202 and/or the one or more memories 104 and 204 of FIG. 19. For example,the transceiver(s) 114 may include the one or more transceivers 106 and206 and/or the one or more antennas 108 and 208 of FIG. 19. The controlunit 120 is electrically connected to the communication unit 110, thememory 130, and the additional components 140 and provides overallcontrol to the wireless device. For example, the control unit 120 maycontrol an electric/mechanical operation of the wireless device based onprograms/code/instructions/information stored in the memory unit 130.The control unit 120 may transmit the information stored in the memoryunit 130 to the outside (e.g., other communication devices) via thecommunication unit 110 through a wireless/wired interface or store, inthe memory unit 130, information received through the wireless/wiredinterface from the outside (e.g., other communication devices) via thecommunication unit 110.

The additional components 140 may be configured in various mannersaccording to type of the wireless device. For example, the additionalcomponents 140 may include at least one of a power unit/battery,input/output (I/O) unit, a driving unit, and a computing unit. Thewireless device may be implemented in the form of, not limited to, therobot (100 a of FIG. 18), the vehicles (100 b-1 and 100 b-2 of FIG. 18),the XR device (100 c of FIG. 18), the hand-held device (100 d of FIG.18), the home appliance (100 e of FIG. 18), the IoT device (100 f ofFIG. 18), a digital broadcasting terminal, a hologram device, a publicsafety device, an MTC device, a medical device, a FinTech device (or afinance device), a security device, a climate/environment device, the AIserver/device (400 of FIG. 18), the BSs (200 of FIG. 18), a networknode, or the like. The wireless device may be mobile or fixed accordingto a use case/service.

In FIG. 20, all of the various elements, components, units/portions,and/or modules in the wireless devices 100 and 200 may be connected toeach other through a wired interface or at least a part thereof may bewirelessly connected through the communication unit 110. For example, ineach of the wireless devices 100 and 200, the control unit 120 and thecommunication unit 110 may be connected by wire and the control unit 120and first units (e.g., 130 and 140) may be wirelessly connected throughthe communication unit 110. Each element, component, unit/portion,and/or module in the wireless devices 100 and 200 may further includeone or more elements. For example, the control unit 120 may beconfigured with a set of one or more processors. For example, thecontrol unit 120 may be configured with a set of a communication controlprocessor, an application processor, an electronic control unit (ECU), agraphical processing unit, and a memory control processor. In anotherexample, the memory 130 may be configured with a RAM, a dynamic RAM(DRAM), a ROM, a flash memory, a volatile memory, a non-volatile memory,and/or a combination thereof.

FIG. 21 illustrates a vehicle or an autonomous driving vehicle appliedto the present disclosure. The vehicle or autonomous driving vehicle maybe implemented as a mobile robot, a car, a train, a manned/unmannedaerial vehicle (AV), a ship, or the like.

Referring to FIG. 21, a vehicle or autonomous driving vehicle 100 mayinclude an antenna unit 108, a communication unit 110, a control unit120, a driving unit 140 a, a power supply unit 140 b, a sensor unit 140c, and an autonomous driving unit 140 d. The antenna unit 108 may beconfigured as a part of the communication unit 110. The blocks110/130/140 a to 140 d correspond to the blocks 110/130/140 of FIG. 20,respectively.

The communication unit 110 may transmit and receive signals (e.g., dataand control signals) to and from external devices such as othervehicles, BSs (e.g., gNBs and road side units), and servers. The controlunit 120 may perform various operations by controlling elements of thevehicle or the autonomous driving vehicle 100. The control unit 120 mayinclude an ECU. The driving unit 140 a may enable the vehicle or theautonomous driving vehicle 100 to drive on a road. The driving unit 140a may include an engine, a motor, a powertrain, a wheel, a brake, asteering device, and so on. The power supply unit 140 b may supply powerto the vehicle or the autonomous driving vehicle 100 and include awired/wireless charging circuit, a battery, and so on. The sensor unit140 c may acquire information about a vehicle state, ambient environmentinformation, user information, and so on. The sensor unit 140 c mayinclude an inertial measurement unit (IMU) sensor, a collision sensor, awheel sensor, a speed sensor, a slope sensor, a weight sensor, a headingsensor, a position module, a vehicle forward/backward sensor, a batterysensor, a fuel sensor, a tire sensor, a steering sensor, a temperaturesensor, a humidity sensor, an ultrasonic sensor, an illumination sensor,a pedal position sensor, and so on. The autonomous driving unit 140 dmay implement technology for maintaining a lane on which the vehicle isdriving, technology for automatically adjusting speed, such as adaptivecruise control, technology for autonomously driving along a determinedpath, technology for driving by automatically setting a route if adestination is set, and the like.

For example, the communication unit 110 may receive map data, trafficinformation data, and so on from an external server. The autonomousdriving unit 140 d may generate an autonomous driving route and adriving plan from the obtained data. The control unit 120 may controlthe driving unit 140 a such that the vehicle or autonomous drivingvehicle 100 may move along the autonomous driving route according to thedriving plan (e.g., speed/direction control). During autonomous driving,the communication unit 110 may aperiodically/periodically acquire recenttraffic information data from the external server and acquiresurrounding traffic information data from neighboring vehicles. Duringautonomous driving, the sensor unit 140 c may obtain information about avehicle state and/or surrounding environment information. The autonomousdriving unit 140 d may update the autonomous driving route and thedriving plan based on the newly obtained data/information. Thecommunication unit 110 may transfer information about a vehicleposition, the autonomous driving route, and/or the driving plan to theexternal server. The external server may predict traffic informationdata using AI technology based on the information collected fromvehicles or autonomous driving vehicles and provide the predictedtraffic information data to the vehicles or the autonomous drivingvehicles.

The embodiments of the present disclosure described above arecombinations of elements and features of the present disclosure. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent disclosure may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent disclosure may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It is obvious tothose skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anembodiment of the present disclosure or included as a new claim by asubsequent amendment after the application is filed.

The embodiments of the present disclosure have been described above,focusing on the signal transmission and reception relationship between aUE and a BS. The signal transmission and reception relationship isextended to signal transmission and reception between a UE and a relayor between a BS and a relay in the same manner or a similar manner. Aspecific operation described as performed by a BS may be performed by anupper node of the BS. Namely, it is apparent that, in a networkcomprised of a plurality of network nodes including a BS, variousoperations performed for communication with a UE may be performed by theBS, or network nodes other than the BS. The term BS may be replaced withthe term fixed station, Node B, enhanced Node B (eNode B or eNB), accesspoint, and so on. Further, the term UE may be replaced with the termterminal, mobile station (MS), mobile subscriber station (MSS), and soon.

Those skilled in the art will appreciate that the present disclosure maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent disclosure. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of thedisclosure should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

The present disclosure may be used in a UE, a BS, or other devices in amobile communication system.

What is claimed is:
 1. A communication method of an apparatus in awireless communication system, the communication method comprising:receiving first downlink control information (DCI); determining a hybridautomatic repeat request-acknowledgment (HARQ-ACK) feedback type basedon the first DCI; and based on the HARQ-ACK feedback type being a firsttype, transmitting a HARQ-ACK feedback of a first physical downlinkshared channel (PDSCH) scheduled by the first DCI, wherein, based on theHARQ-ACK feedback type being a second type, the HARQ-ACK feedback of thefirst PDSCH is not transmitted, or a HARQ-ACK feedback of a second PDSCHis transmitted, and the second PDSCH is scheduled by second DCI, and thesecond DCI is received before the first DCI, wherein the HARQ-ACKfeedback type is determined to be the second type based on a 1-bit flagin the first DCI, wherein, based on the HARQ-ACK feedback type being thesecond type, whether the HARQ-ACK feedback of the first PDSCH is nottransmitted or the HARQ-ACK feedback of the second PDSCH is transmittedis determined based on a specific field included in the first DCI, andwherein the specific field is different from the 1-bit flag.
 2. Thecommunication method according to claim 1, wherein, based on theHARQ-ACK feedback type being the second type, the HARQ-ACK feedback ofthe second PDSCH is transmitted based on first transmission timinginformation by ignoring second transmission timing information, andwherein the first transmission timing information is included in thefirst DCI, and the second transmission timing information is included inthe second DCI.
 3. The communication method according to claim 1,wherein, based on the HARQ-ACK feedback type being the second type, thefirst DCI does not schedule a PDSCH and the HARQ-ACK feedback of thesecond PDSCH is transmitted.
 4. The communication method according toclaim 1, wherein the HARQ-ACK feedbacks of the first PDSCH and thesecond PDSCH are transmitted in an unlicensed band (U-band).
 5. Thecommunication method according to claim 1, wherein the first DCI isreceived during a discontinuous reception (DRX) on duration configuredfor the apparatus.
 6. An apparatus configured to operate in a wirelesscommunication system, the apparatus comprising: a memory; and aprocessor, wherein the processor is configured to: receive firstdownlink control information (DCI); determine a hybrid automatic repeatrequest-acknowledgment (HARQ-ACK) feedback type based on the first DCI;and based on the HARQ-ACK feedback type being a first type, transmit aHARQ-ACK feedback of a first physical downlink shared channel (PDSCH)scheduled by the first DCI, wherein, based on the HARQ-ACK feedback typebeing a second type, the HARQ-ACK feedback of the first PDSCH is nottransmitted, or a HARQ-ACK feedback of a second PDSCH is transmitted,and the second PDSCH is scheduled by second DCI, and the second DCI isreceived before the first DCI, wherein the HARQ-ACK feedback type isdetermined to be the second type based on a 1-bit flag in the first DCI,wherein, based on the HARQ-ACK feedback type being the second type,whether the HARQ-ACK feedback of the first PDSCH is not transmitted orthe HARQ-ACK feedback of the second PDSCH is transmitted is determinedbased on a specific field included in the first DCI, and wherein thespecific field is different from the 1-bit flag.
 7. The apparatusaccording to claim 6, wherein, based on the HARQ-ACK feedback type beingthe second type, the HARQ-ACK feedback of the second PDSCH istransmitted based on first transmission timing information by ignoringsecond transmission timing information, and wherein the firsttransmission timing information is included in the first DCI, and thesecond transmission timing information is included in the second DCI. 8.The apparatus according to claim 6, wherein, based on the HARQ-ACKfeedback type being the second type, the first DCI does not schedule aPDSCH and the HARQ-ACK feedback of the second PDSCH is transmitted. 9.The apparatus according to claim 6, wherein the HARQ-ACK feedbacks ofthe first PDSCH and the second PDSCH are transmitted in an unlicensedband (U-band).
 10. The apparatus according to claim 6, wherein theprocessor is configured to receive the first DCI during a discontinuousreception (DRX) on duration configured for the apparatus.
 11. Theapparatus according to claim 6, wherein the apparatus includes anautonomous driving vehicle communicable with at least one of a userequipment (UE), a network, or another autonomous driving vehicle otherthan the apparatus.